Ariane Lambert-Mogiliansky

Konstantin Sonin

Ekaterina Zhuravskaya

Normale École

Supérieure

Erik Berglöf

Rick Ericson

Rafael La Porta

Peter Murrell

Yingyi Qian

Gèrard Roland

Andrei Shleifer

Jean Tirole

Daniel Treisman

Are Russian commercial courts biased? Evidence from a natural bankruptcy experiment

Keywords: K42, P26 bankruptcy, transition, capture

Abstract:

We study the nature of judicial bias in bankruptcy proceedings following the enactment of bankruptcy law in Russia in 1998. We find that regional political characteristics affected judicial decisions about the numbers and types of bankruptcy procedures initiated after the law took effect. In particular, controlling for indicators of firms' insolvency and the quality of the regional judiciary, reorganization procedures were significantly more frequent in regions with politically popular governors and governors who had hostile relations with the federal government. Poor judicial quality was also associated with higher incidence of reorganizations. In addition, the quality of the regional judiciary affected performance of firms in reorganization procedure: in regions with poor judicial quality firms in reorganization significantly underperformed firms not in bankruptcy; while the opposite was true in regions with high-quality judges. The effect of judicial quality on restructuring is particularly strong in regions with politically popular governors because the judicial bias in governor's favor is the highest in poor-quality courts when governors are popular. This evidence is consistent with previously reported anecdotes, which suggested that politically strong regional governors used bankruptcy proceedings to protect firms from paying federal taxes.

Introduction

Laws and regulations that perfectly fit into a well-developed market economy might bring unexpected outcomes when transplanted to an emerging market. The performance of legal rules depends upon the environment in which they are applied. Enforcement and application of legal rules can be subverted by powerful actors who have political influence over law enforcers [START_REF] Glaeser | The Injustice of Inequality[END_REF]. In addition, law enforcers themselves may have their own career concerns or preferences for fairness and social justice that dictate them to apply the law differentially [START_REF] Gennaioli | The Evolution of Precedent[END_REF]. Enactment of Russia's 1998 Bankruptcy Law provides a natural experiment for studying mechanisms behind poor law enforcement. Prior to the enactment of the law, there was virtually no bankruptcy institution. As a result, many firms had accumulated tax arrears and overdue debts and were candidates for bankruptcy after the enactment of the 1998 law. Only a very small fraction of them actually went bankrupt. Selective application of the law allows us to study the biases in law enforcement. 1 The results help drawing general lessons on how to transplant legal rules and design them from scratch in emerging markets.

The main goals of Russia's 1998 Bankruptcy Law were to restructure loss-making enterprises or close them down (if restructuring was not possible) and to provide creditors with an effective tool of debt recovery. In 1997, the share of loss-making enterprises in Russia was about 50%, and total overdue loans and taxes amounted to 30% of GDP, of which overdue tax liabilities to the consolidated budget were about 7% of GDP (Goskomstat, 1999). The Law had been drafted according to up-to-date academic standards (e.g., EBRD, 2000aEBRD, , 2000b;;[START_REF] Black | A Self-Enforcing Model of Corporate Law[END_REF][START_REF] Porta | Law and Finance[END_REF]. EBRD (2000b) stated: "If applied, consistently within the language of the law, the Russian [insolvency] system may result in the same or greater recovery for a secured creditor than results from many Western systems. …it could be argued that the Russian bankruptcy system adequately addresses the creditors' bargain and common pool issues…" 2 Yet, the law failed to achieve the intended goals: after its enactment, recovery rates remained low and restructuring was going very slowly. According to Goskomstat (2001), even after the full recovery from the 1998 crisis the share of Russian loss-making enterprises in 2000 was above 37% and bankruptcy was initiated against no more than 2% of insolvent firms. The World Bank reports that recovery rates remained below 50% in 2004(Doing Business, World Bank, 2005).

Using firm-level data on the application of the law, we test a hypothesis suggested by voluminous anecdotal evidence that the driving force behind the law's poor enforcement was its subversion by regional governors -the second tier in the three-tiered federalist system in Russia. We find systematic evidence that regional governors had significant influence over law enforcers. In particular, the political strength of regional governors and their relationship with the federal authorities was a major determinant of the number and type of bankruptcy proceedings initiated by regional commercial courts after the enactment of the 1998 Bankruptcy Law.

The fact that the governors managed to affect outcomes of bankruptcy proceedings is an interesting and, to some extent, unexpected finding. Regional governors were competing for influence over law enforcers with a wealthy and powerful coalition of Moscow-based banks owned by Russian "oligarchs" and the federal government who were the major creditors of Russian firms at the time. The federal government was primarily concerned with collecting federal tax arrears; whereas the oligarchic banks were interested in gaining control over non-paying enterprises in addition to simple debt recovery. In contrast, regional governors, often in coalition with incumbent managers of firms, were interested in keeping financial resources and control over assets in their own hands. The oligarchs had substantially more resources to bribe law enforces compared to the regional governors or incumbent managers. The federal government, had it been politically strong, would have had means of influence both over the regional governors and judges. Nonetheless, anecdotal evidence (e.g., [START_REF] Black | Russian Privatization and Corporate Governance: What Went Wrong?[END_REF][START_REF] Moss | Bankruptcy Reform in Russia: The Case for Creditor Rights in Russia[END_REF][START_REF] Volkov | The Selective Use of State Capacity in Russia's Economy: Property Disputes and Enterprise Takeovers, 1998-2002[END_REF] suggests that the regional governors' political control over the judiciary allowed them to leave the federal government and oligarchs empty-handed. 3 In a sociological study, [START_REF] Volkov | The Selective Use of State Capacity in Russia's Economy: Property Disputes and Enterprise Takeovers, 1998-2002[END_REF] describes the mechanism of subversion of the 1998 Bankruptcy Law and illustrates it with a few examples: The reorganization procedure was used by governors in order to protect firms from paying federal taxes and repaying debt to Moscow-based banks. The automatic stay on assets provision of the bankruptcy law was used to freeze their claims, and firms continued their usual operations, while being formally under protection provided by the reorganization procedure. In many cases, the incumbent managerial team remained in control over the firms under reorganization: formally, the top manager was replaced by his/her closest ally. This 3 Federal tax arrears were growing throughout the 1990s. In the beginning of 1998, they reached 5% of Russia's GDP. [START_REF] Cai | State Corroding Federalism[END_REF], [START_REF] Sonin | Provincial Protectionism[END_REF], and [START_REF] Ponomareva | Federal Tax Arrears: Liquidity Problems, Federal redistribution, or Regional Protection?[END_REF] discuss theory and evidence of regional governors' protection of firms from paying federal taxes. [START_REF] Shleifer | Without a Map: Political Tactics and Economic Reform in Russia[END_REF] discuss the reasons and the consequences of federal government's political weakness.

was contrary to the law prescription, which postulated that incumbent managers should be deprived of control over the firm and a bankruptcy practitioner should be appointed to run the firm on creditors' approval. Sometimes, the incumbent management team was replaced by managers who had closer ties with the regional governor. Presumably, this happened when the incumbent managers and the governors could not agree on the terms of sharing the rents from expropriation of creditors and the federal budget. In addition, in some circumstances judges had the power to prolong reorganization proceedings for the so-called "socially important" enterprises up to 10 years. This clause of the law was often used to maintain the status quo for years so that managers with close ties to regional governors could stay in control, while the federal government and the Moscow-based banks could not recover their claims. Irrespective of what happened to the incumbent management, the bias of bankruptcy court judges towards regional political powers undermined the idea of bankruptcy as an institution that protects creditor rights.

Why commercial courts may depend on regional authorities? There is no single systematic study of the incentives of commercial court judges. Presumably, there are two underlying reasons for the judicial bias. First, judges depend on regional authorities in their career prospects: after retiring from service in commercial courts, they often continue to work in regional administrations and regional state enterprises as lawyers. Anecdotal evidence suggests that there is virtually no interregional or vertical mobility among the lowest-tier commercial judiciary. Moreover, appointments of regional judges require approval of regional authorities. Second, the political and geographical distance from the federal center forces judges to adhere to the regions socially. The best-known example of dependence of commercial court judges on regional political elites was the bankruptcy proceedings of the oil holding Sidanko and its key subsidiaries Chernogoneft and Kondopetroleum in 1999. During Chernogoneft bankruptcy proceedings, 98% of the creditors voted for a certain bankruptcy practitioner, but the judge overruled their decision and appointed a different candidate connected to another oil company, Tyumen Oil. The court also rejected the offer by Chernogoneft, already in bankruptcy, to pay all creditors in full. Incidentally, the Tyumenskaya Oblast Governor, Leonid Roketsky, happened to be the Chairman of the Board at Tyumen Oil. The latter bought Chernogoneft for $176 million and Kondpetroleum for $52 million (a small fraction of the actual market value). Black, Kraakman, and Tarasova (2000) wrote: "… Apparently, […] Tyumen Oil didn't merely bribe judges (Sidanko could have offered its own bribes), but threatened them as well…" The Economist (Dec. 4, 1999) wrote that according to allegations of one of the competitors to Tyumen Oil's, the company intimidated judges; in addition, Sidanko complained that: "If they just stuck to bribing judges, we could play that game too."

The evidence is not confined to the Tymen oblast. The so-called Governor's Off-budget Fund, formed in 1997 in Kemerovskaya oblast, provides another example of well-established political ties between regional governors and large firms, on the one hand, and commercial court judges, on the other. According to a national Russian daily Izvestia (September 16, 1999), a deeplytroubled West-Siberian Metallurgy Kombinat (ZapSib, Kemerovo's biggest steel plant) despite being in the middle of bankruptcy proceedings, regularly contributed to the governor's Fund with the consent of the judge, while accumulating large federal tax arrears. Such contributions are a direct violation of the law. Under the governor-controlled reorganization procedure, the company debts increased to about $400 million from $130 million (New York Times, 2000). 4In this paper, we provide systematic evidence that the application of the law was, indeed, biased in favor of regional authorities. Our empirical strategy is twofold. First, we look at how the initial (i.e., taken before the enactment of the new law) regional factors influenced the probability of a firm to fall into either the reorganization or the liquidation proceedings after the enactment of the law, holding the level of firms' financial health constant. We find that reorganization procedures were more frequently initiated against firms in regions with politically strong governors (who exercised control over courts more easily) and in regions with a higher degree of political independence from the federal center (which made it less politically costly for the governors to expropriate federal tax revenues). In contrast, liquidation procedures were less frequently initiated against firms in regions with high degree of political independence from the federal center.

Second, we test whether firms that found themselves in reorganization procedures after the enactment of the law restructured, as dictated by the law, or did not, as the story of bankruptcy subversion by regional governors would suggest. We find that in regions with a particularly bad quality of the regional judiciary (due both to low skills and regional bias of judges), firms in reorganization demonstrated significantly lower growth rates in sales, labor productivity, and product varieties compared to similar firms not in bankruptcy. In contrast, in regions with highquality judges, the opposite was true: firms in reorganization outperformed firms outside bankruptcy in terms of growth indicators. The effect of poor judicial quality on performance is stronger in regions with politically popular governors because in these regions the bias in governor's favor in poor-quality courts is the greatest. These findings are consistent with the view that politically strong governors subverted enforcement of the bankruptcy law in Russia.

By analyzing the consequences of a legal transplant to a weakly institutionalized environment, our paper contributes to the literature on legal transplants (i.e., Berkowitz, Pistor, andRichard, 2003a, 2003b;[START_REF] Pistor | Law and Finance in Transition Countries[END_REF]. We also contribute to the literature on comparative bankruptcy law by analyzing workings of the law enforcement in different institutional environments (see, for instance, [START_REF] Aghion | The Economics of Bankruptcy Reform[END_REF][START_REF] Hart | Different Approaches to Bankruptcy[END_REF][START_REF] Bolton | Towards a Statutory Approach to Sovereign Debt Restructuring: Lessons from Corporate Bankruptcy Practice Around the World[END_REF][START_REF] Ayotte | Matching Bankruptcy Laws to Legal Environments[END_REF][START_REF] Povel | Optimal `Soft' or `Tough' Bankruptcy Procedures[END_REF]World Bank, 2004[START_REF] Shvets | Judicial Bias in Russian Commercial Courts[END_REF][START_REF] Berkovitch | Optimal bankruptcy laws across different economic systems[END_REF][START_REF] Claessens | Bankruptcy Around the World: Explanations of its Relative Use[END_REF][START_REF] Djankov | Private Credit in 129 Countries[END_REF]. Our findings also have relevance to the literature on Russia's federalism [START_REF] Qian | Federalism as a Commitment to Preserving Market Incentives[END_REF][START_REF] Shleifer | Without a Map: Political Tactics and Economic Reform in Russia[END_REF][START_REF] Sonin | Provincial Protectionism[END_REF][START_REF] Cai | State Corroding Federalism[END_REF][START_REF] Zhuravskaya | Incentives to Provide Local Public Goods: Fiscal Federalism, Russian Style[END_REF][START_REF] Ponomareva | Federal Tax Arrears: Liquidity Problems, Federal redistribution, or Regional Protection?[END_REF], since we document that the bankruptcy institution is used by regional governments as a mechanism for redistributing tax revenue from the federal center to the regions.

The rest of the paper is organized as follows. Section 2 describes institutional background and presents details of the bankruptcy legislation and basic statistics. Section 3 describes the results of econometric analysis. Section 4 concludes.

Institutional background

Commercial courts

In Russia, bankruptcy cases are decided by commercial ("Arbitrazh") courts. In 1991, Russia entered economic transition with "Gosarbitrazh", a state judicial organ. Gosarbitrazh decided cases primarily based on either the current considerations of fulfillment of five-year plans, or direct political orders; whereas law did not enter into consideration [START_REF] Hendley | The Effectiveness of Legal Institutions in the Transition Economy in Post-Soviet Russia[END_REF]. In 1991, judicial reform established commercial courts as a state tribunal charged with resolving business disputes.

Since 1995, Russian commercial courts have been organized in three-tier system. There are 81 courts of first instance (i.e., regional courts), ten appellate courts, and one Higher Arbitrazh Court, which is the commercial court of last instance.

The most commonly considered cases by commercial courts are contractual disputes, tax disputes between firms and federal government, disputes over ownership of property, use of land, antitrust, environmental and customs regulation, as well as over registration, licensing and certification. The next most common type of cases considered in commercial courts is bankruptcy proceedings. (See [START_REF] Hendley | The Effectiveness of Legal Institutions in the Transition Economy in Post-Soviet Russia[END_REF], for a detailed information on the dynamics of caseload.)

It is important for our story that the law requires the plaintiff to file a suit in the commercial court of the first jurisdiction (regional court) of the region, where the defendant is officially registered. This prevents competition between different regional courts (see, for instance, [START_REF] Shvets | Judicial Bias in Russian Commercial Courts[END_REF]. Jurisdictions of each of the regional courts coincides with the administrative borders of their respective regions. The ties between regional judges and regional authorities in many regional courts have been very strong throughout the second half of 1990s. First, since 1995, judicial appointments required consent of regional authorities. Formally, all nominations to the positions of judges in regional commercial courts (done by the qualifying committee of judges) are approved by the regional legislative assembly, which in many regions is under political control of the governor, i.e., the top regional executive.

The law requires commercial courts be financed only from the federal budget. Nonetheless, anecdotal evidence suggests that the lack of federal financing lead to a common situation, in which regional governments covered a large part of courts expenses from the regional budgets and even supplemented judges' salaries.

There is no agreement in the literature on the quality of Russian commercial courts. [START_REF] Hendley | Law Works in Russia: The Role of Legal Institutions in the Transactions of Russian Enterprises[END_REF] survey Russian entrepreneurs to find that commercial court judges are regarded as having high ethical standards; they conclude that the commercial court system is less corrupt relative to other institutions in Russia. (In their survey, there were no questions on the integrity of judges in bankruptcy proceedings, however.) In addition, [START_REF] Hendley | The Effectiveness of Legal Institutions in the Transition Economy in Post-Soviet Russia[END_REF] argues that there are relatively small delays in commercial court hearings. In contrast, Black and Tarasova (2000) make a case that commercial courts in Russia are very corrupt and have almost no experience in dealing with complicated business cases. [START_REF] Black | A Self-Enforcing Model of Corporate Law[END_REF] and [START_REF] Hay | Private Enforcement of Public Laws: A Theory of Legal Reform[END_REF] discuss evidence of frequent severe delays in court hearings.

Bankruptcy legislation

Russia has had the bankruptcy legislation since November 1992. (Although the first Russia's bankruptcy regulation was adopted in 1740, there were no bankruptcy institution during the last five decades of the Soviet regime.) The 1992 bankruptcy law was completely ineffective: between 1992 and 1998, very few companies went bankrupt. The failure of this law to bring about financial discipline was due to the limited scope of its application and excessively complicated procedures. In order to initiate a bankruptcy procedure according the 1992 law, the total amount of outstanding debt had to exceed the total book value of a company's assets. In practice, a company manager could simply issue worthless debt to his own firm at a high face value to avoid bankruptcy. Thus, for Russia's companies, courts, and tax collectors, there was no operational bankruptcy legislation in Russia before 1998.

The law of 1998 was supposed to amalgamate best parts of the U.S. and UK Bankruptcy Codes and make the initiation of bankruptcy very easy. Formally, under the 1998 law, if a creditor filed a bankruptcy petition, the following procedure was undertaken. First, a temporary manager, appointed by a bankruptcy court judge, collected information about the claims on the company and organized a creditor meeting. At the meeting, the creditors decided if they wanted liquidation or reorganization. Second, the judge made a ruling on the liquidation or reorganization of the company, taking into consideration the resolution of the creditor meeting. The judge appointed a "liquidation manager" if a liquidation was ordered, or an "external manager" if a reorganization was ordered.

The judge did not necessarily need to follow the creditors' request. This clause in the law was motivated by the fact that creditors may opt for an inefficient liquidation. Initiation of both procedures was supposed to deprive the incumbent management of control over the firm.

Thus, the main features of the 1998 law were (i) the dismissal of management upon filing, aimed at hardening budget constraints for managers, and (ii) the judicial discretion to mitigate creditors' tendency to over-liquidate, in case survival is socially efficient. These two features were in contrast with the U.S. bankruptcy law, which emphasized debtor-in-possession but offers judges fewer opportunities to mandate reorganization than the Russian law. The reorganization procedure according to the 1998 the Russian bankruptcy law was much harsher on the incumbent management compared to Chapter 11 of the U.S. bankruptcy law and less creditor-friendly than the U.K.'s reorganization procedure, which allowed creditors' full control.

In December 2002, a new bankruptcy law was adopted. Although changes introduced by the new law aimed at reducing an outright fraud frequent under the 1998 law, most features important for our story remained intact (see Thompson, 2002, for an overview of main changes).

Basic bankruptcy statistics

The Russian 1998 law was expected to vastly improve managerial incentives because it was supposed to be harsh on the incumbent management. This was in drastic contrast to legislation in place prior to 1998. The result should have been an improvement of creditor protection, and thus, ex-ante efficiency, which is considered crucial for financial development (e.g., von [START_REF] Thadden | Optimal Debt Design and the Role of Bankruptcy[END_REF][START_REF] Porta | Legal Determinants of External Finance[END_REF], 1998, 2000). The hope was that the law would boost development of private credit institutions. In terms of private credit to GDP ratio, Russia was on 84 th place out of 129 countries [START_REF] Djankov | Private Credit in 129 Countries[END_REF]. Indeed, since the law was adopted, the bank credit as percentage of GDP increased as shown in Figure 1 and so did the number of initiated bankruptcy procedures, as shown in Table 1. These two facts were often interpreted by policymakers as hard evidence of an overall success of the bankruptcy reform. Such interpretations, however, may be misleading. One has to be very careful in drawing welfare conclusions from these facts. First, an increase in (private) credit can be a consequence of soft budget constraints [START_REF] Maskin | Soft budget constraint theories: From centralization to the market[END_REF], rather than an indication of improvement in ex-ante efficiency. This is particularly likely in transition economies. For instance, this is the reason why private credit to GDP ratio in China is above that in many financially developed countries, e.g. Germany and France [START_REF] Djankov | Private Credit in 129 Countries[END_REF]. Second, bankruptcy procedures were initiated primarily against flyby-night firms that had been created primarily for tax evasion purposes and disappeared shortly after registration, while the vast majority of loss-making firms continued to operate, unaffected by bankruptcy. (The 1998 law had no special procedure for the liquidation of an absent debtor.)

Analysis in this paper shows that the law had different effect in different regions depending on the quality of the regional judiciary and political strength of regional governors.

Table 2 summarizes basic firm-level characteristics in 1997 for three groups of firms: 1) all firms, 2) firms that fell into reorganization procedure in 1998, and 3) firms that fell into liquidation procedure in 1998. The three groups differ both in the average size of firms and average basic performance characteristics, such as labor productivity, labor productivity growth and profitability.

As one would expect, firms under liquidation were the worst performers, on average, whereas firms unaffected by bankruptcy procedures were the best. The most noticeable difference among the three groups is the firms' size. Liquidation procedures were initiated primarily against small and mediumsize enterprises. In contrast, reorganization procedures were initiated against much larger enterprises. On average, sales of firms under reorganization were fifteen times larger compared to sales of firms that entered a liquidation procedure; and the difference in the number of employees was fourfold. Political economy literature explains why politicians may be opposed to liquidation of large companies and why there can be too few liquidation procedures (e.g., [START_REF] Shleifer | Politicians and Firms[END_REF][START_REF] Boycko | A Theory of Privatization[END_REF][START_REF] Tornell | Privatizing the Privatized[END_REF][START_REF] Kornai | Understanding the Soft Budget Constraint[END_REF]. Thus, it is not surprising that small firms were liquidated, while large firms were reorganized after the new law took effect. In this paper, we show that preferences for the choice of liquidation and reorganization diverged in the federal and regional governments in Russia.

Analysis

Data

We compiled data from the following sources: the list of publicly announced reorganization procedures initiated in 1998 and the first half of 1999 comes from the "Internet Securities" (www.securities.ru) and the AK&M news service (www.disclosure.ru) data bases; a comprehensive list of liquidation procedures initiated in 1998 and the first half of 1999 comes from the Higher Bankruptcy Court Journal (Vestnik Vysshego Arbitrazhnogo Suda); data on firms in 1996-1999 were obtained from the Russian Enterprise Registry Longitudinal Database (RERLD, the annual census of large and medium-size industrial enterprises); firm-level financial data come from the ALBA data set of balance sheets for large Russian industrial firms; regional statistical data come from statistical abstracts Regions of Russia, 1999, the official web site of the Russia's State Tax Agency, MFK Renaissance, Central Elections Commission of RF, and Shvets (2005).5 3.2. Did regional political characteristics influence the type of bankruptcy procedures?

Our main hypothesis is that regional courts are biased in favor of the regional governors.

The two alternatives that we consider are as follows: commercial court judges are either unbiased in their decisions, or they are biased against regional governors in favor of the federal government and Moscow-based banks (i.e. firms' main creditors). These three alternative hypotheses about the biases of the regional judiciary generate different predictions for the firms' likelihood of going into reorganization or liquidation. We focus on how the ex ante characteristics of the firms, their industries, and regions (before the 1998 law was adopted) influenced the odds that these firms ended up in either reorganization or liquidation procedure, or were not affected by either procedure. In particular, we are interested in whether regional political variables affect the probability of a bankruptcy procedure in a firm controlling for its financial health. We consider the following three main regional-level explanatory variables.

(1) Governor's popularity

If judges potentially consider the regional governor's opinion in their rulings, one would expect that the bias towards governors would be stronger for more popular and, thus, politically strong governors than for less popular and, thus, politically weak governors. We use the share of the votes received by the governor in the first round of the latest regional election prior to the enactment of the 1998 bankruptcy law as a proxy for the governor's popularity (we denote this variable as P). If the regional governors influence court decisions and use reorganization procedure as the tool to protect firms from paying federal taxes and debts (as much of anecdotal evidence suggests), one should expect to see more reorganizations in regions with more popular governors. In addition, since liquidations are politically costly, we expect to see fewer liquidation procedures when governors are popular. If courts are independent or biased toward creditors, the political strength of the governor should not matter for the numbers or types of bankruptcies.

(2) Federal-regional hostility Both the federal and the regional authorities may potentially have preference towards reorganization over liquidation simply because politicians prefer not to close down firms for political reasons. Yet, if the hypothesis of the regional subversion of the bankruptcy institution is true, there is a direct conflict between regional and federal authorities in which the regional government uses reorganizations to freeze out federal tax claims. Thus, we would expect the governors that were in open political opposition to the federal center to be more active in using bankruptcy as a mechanism of expropriation of the federal center. More hostility in the relationship of the governor and the federal center implies lower political costs of opposition to the center in general, and in bankruptcy proceedings in particular. Thus, if courts are biased in favor of regional governors, we would expect reorganizations to be more likely when political relationship between the president and the governor are strained. Moreover, as the federal government is fiscally motivated, we would expect liquidations to be more likely when regional and federal governments are friendly to each other compared to a situation when they are at odds with each other and the courts are biased in favor of regional governors. We use an index constructed by MFK Renaissance, H, to measure how hostile the political relationships of the governor and the federal government were in 1997 (larger values mean more hostility). This index uses information on 1) the frequency of public statements by the governor against the policies of the federal center, 2) the extent to which regional laws and regulations violate federal laws, 3) the level of support to the governor by the president at the latest regional election, and 4) the presence of a bilateral treaty between the region and the center.

(3) Judicial Quality

We also use a measure of regional judicial quality (J) as one of our main explanatory variables. The measure was constructed and used by [START_REF] Shvets | Judicial Bias in Russian Commercial Courts[END_REF]. It is equal to the average rate of approvals of decisions of regional commercial courts during appeals in higher-jurisdiction commercial courts between 1995 and 2002. 6 Shvets (2005) argues that it is well known that higherlevel commercial courts are comprised of much better skilled, motivated, and career-oriented judges.

Thus, the rulings of the higher-jurisdiction judges have much lower probability of either being biased or erroneous due to a simple mistake. (The reason why this is not a panacea for Russian judicial system to appeal to the higher-level court is that only a very small share of cases goes through the higher-jurisdiction commercial courts due to very long delays in consideration and other technical barriers for appeal.) Thus, J measures the average share of correct rulings by regional-level judges. The faulty rulings may, of course, be both due to simple errors (in which case, the variable picks up the level of judicial skills) and deliberate biases of the regional-level judiciary (in which case the variable picks up judicial independence). If the average approval rate is high, the judicial biases are small and courts do not make many random mistakes.

If bankruptcy courts are biased toward regional political authorities, our measure of judicial quality should negatively affect the likelihood that a firm goes into reorganization, since the higher the average approval rate, the smaller the court bias. The same logic suggests that the number of liquidations should decrease when judicial quality increases, since governors are not interested in liquidation. If, in contrast, courts are biased toward the coalition of the federal government and Moscow banks, then an increase in judicial quality might have a positive effect on both reorganizations and liquidations, since the federal government and Moscow-based banks may or may not want to liquidate a distressed firm as their first choice depending on its main objectives.

The federal government may prefer reorganization for political reasons and the banks may also prefer reorganization for financial reasons if the industry is liquidity-constrained. Reorganization would probably imply a management change, as required by the bankruptcy law. We expect the law to be enforced in this case because courts are biased in the federal government's favor. Finally, if courts are independent, judicial quality may have an ambiguous effect on creditors' passivity (and thus on the likelihood of reorganization / liquidation) depending on how risk-averse or risk-loving creditors are. 7 We estimate the Multinomial Logit regression model on the cross-section of firms. The dependent variable is the probability that a firm, given its characteristics before the adoption of the 1998 law, (1) falls into an reorganization procedure, (2) is liquidated, or ( 3) is unaffected by bankruptcy during a year and a half after the introduction of the new law. We look at ex ante characteristics of firms to avoid endogeneity and rule out any reciprocal effects of bankruptcy onto firm characteristics. Our sample consists of 7,815 firms that are drawn from the intersection of RERLD, ALBA, and regional data sets for 1997. 7 As we would expect in the case of a regional bias in commercial courts, there is a negative correlation (of -0.17) between governor popularity and regional judicial quality. Federal-regional hostility and regional judicial quality are weakly positively correlated. Figure A1 in appendix presents non-parametric relationships between our main explanatory variables.

The estimated equation is as follows:

) J H P ( F ] j B Pr[ i i 4 i 3 i 2 i 1 i ε + β + β + β + β = = X (1)
where i identifies a firm in the sample. B i is an outcome after the introduction of the new law: it is equal to one of the three following outcomes for each firm in 1998 and the first half of 1999: 0bankruptcy procedure was not initiated (comparison group), 1-reorganization procedure was initiated, and 2-liquidation procedure was initiated. F is a logistic function.

The following variables are used as controls. First, we control for the firm-level characteristics that influence the probability that firm ends up in bankruptcy: leverage ratio (log debt-to-assets ratio), coefficient of current liquidity (log ratio of liquid assets to short term liabilities), log cost per unit of output, log labor productivity, log labor productivity growth, log of official employment, and three-digit industry dummies. Firm-level controls are necessary to analyze the effect of regional characteristics of firms that, otherwise, would have similar prospects in bankruptcy. Second, we control for gross regional product per capita. This is an important control because political characteristics of the regions that we are interested in may be correlated with the regional economic development, which, in turn, may affect the number of regional bankruptcy procedures. All control variables are measured in 1997, before the introduction of the new law.

Table 1A (see Appendix) presents summary statistics for the variables used in the regression analysis. We correct the standard error for heteroskedastisity and clusters of i ε within combinations of the regions and two-digit industries [START_REF] Krishnaiah | Handbook of statistics[END_REF].

Table 3 presents the regression results. We report both the coefficients of the Multinomial Logit regression and marginal effects evaluated at the mean levels of independent variables for the reorganization and liquidation outcomes, holding no bankruptcy as the comparison group.

The hypothesis of a regional bias finds support in the data. As predicted, controlling for firmlevel characteristics, the probability of the reorganization procedure initiated against a firm in a region after the enactment of the 1998 bankruptcy law was positively significantly associated with the political popularity of the regional governor (which makes it easier for him to extend his influence on courts), with the extent of regional hostility towards the federal center (which makes it less politically costly for the governor to oppose the federal center), and with the extent of deficiencies in regional commercial courts. The probability of a liquidation procedure is unaffected by the governor's popularity or judicial quality but is negatively and significantly related to a higher degree of hostility in political relations between the region and the federal center. This is consistent with our assumption that the primary motivation for the federal government is fiscal, and thus it would like to liquidate inefficient firms; while the politically-motivated regional government wants to keep the firms in operation. These results are very robust: they do not depend on a particular specification or a particular set of covariates.

The economic significance of these results is as follows. A one standard deviation increase in the measure of governor's popularity leads to a 2.88% increase in the predicted probability that an average firm ends up in reorganization procedure. In addition, a one standard deviation increase in the regional hostility towards the federal center is associated with a 4.91% increase in the predicted probability of a reorganization procedure. The numbers are based on predicted probability of reorganization that is evaluated at the mean value of employment for firms under reorganization procedure and overall means for all other independent variables. (It is equal to 1.71%.) In addition, a one standard deviation increase in judicial quality leads to a 4.31% decrease in the probability of reorganization.

In contrast, a one standard deviation increase in the regional hostility towards the federal center decreases the probability that an average firm ends up in liquidation by 9.02% of the predicted probability of this outcome. This predicted probability is evaluated at the mean value of employment for firms that are being liquidated and overall means for all the other covariates, which is equal to 0.03%. The numbers are rather small, as most firms in the sample have been unaffected by bankruptcy.

Signs of the coefficients of control variables are also as expected: low levels of current liquidity and labor productivity significantly increase the probability of both bankruptcy procedures.

As predicted by political economy models, in which politicians and judges care about employment, we find that firms that end up in liquidation are significantly smaller than average. The size of firms that end up in reorganization procedure is, however, above the size of firms that are unaffected by bankruptcy. This is consistent with our basic story because the regional governments are more likely to use reorganization procedure to protect large rather than small firms from the federal government and creditors.

If bankruptcy were politically independent, regional political variables should have no effect on the probability of bankruptcy procedures unless these variables were correlated with the regional economic distress and we did control for this properly. In this case, however, regional political variables should have had the same effect on the probability of both bankruptcy procedures. In contrast, we find the opposite effects of regional political variables on the probability of reorganization and liquidation procedures holding firm characteristics constant. The governor's political strength and hostility towards the center do not seem to correlate with the regional economic distress. The correlation coefficients of these variables with various available measures of the regional economic well-being (for instance, per capita growth, index of resource potential, ratio of per capita income to subsistence level, etc.) are small, positive, and insignificant.

3.3. Did reorganization procedures induce restructuring in bankrupt firms?

In this section, we investigate three issues: First, we test whether firms, which found themselves in reorganization procedures after the enactment of the 1998 Bankruptcy Law, restructured as they were supposed to do, or did not restructure as our story of subverted bankruptcies suggests. On average, we should not observe any restructuring following the initiation of reorganization procedures, as these were initiated primarily in order to protect firms from paying federal taxes and overdue debt, rather than reorganize.

Second, we test whether restructuring efforts for firms under the reorganization procedures vary with judicial quality. Poor judicial quality means a higher scope for influence over court decisions. Thus, our prediction is that one should observe relatively less restructuring in firms in reorganization if the court quality is poor.

Third, judicial bias towards regional governors would be particularly strong if the political popularity of the governor is high and the quality of courts is poor. Thus, we expect a stronger effect of poor judicial quality on restructuring in bankruptcy in the regions with popular governors. We test whether data supports this prediction.

We compare several performance measures in similar firms belonging to two groups: 1) a group of firms that started reorganization procedure in 1998 and 2) a control group. The control group is comprised of two firms (if they exist) for each firm in reorganization. The two firms are chosen from the same five-digit industry as the firm in reorganization, such that they are the closest to the firm in size (one smaller, and another one larger).

We use the following three proxies for restructuring: log change in sales, log change in labor productivity, and log number of new product varieties between 1998 and 1999. We run OLS regressions for each of these proxies on the dummy indicating reorganization procedure and the interaction of the reorganization dummy with judicial quality as well as the triple interaction term of reorganization, judicial quality, and governor's popularity.

We estimate the following two equations:

i i 4 i 3 i i 2 i 1 i J ) J J ( R R Y ε + β + β + - β + β = X and (2)
i i 8 i i 7 i i 6 i 5 i 4 i i i 3 i i 2 i 1 i P J ) P P ( R P J ) P P )( J J ( R ) J J ( R R Y ε + β + β + - β + β + β + - - β + - β + β = X (3)
where i indexes firms, Y stands for one of the three measure of enterprise restructuring, R is the dummy indicating firms under reorganization proceedings, J and P indicate our two regional variables of interest: judicial quality and governor's popularity, respectively. Thus, we estimate the effect of judicial quality on restructuring inside bankruptcy procedure using difference-indifferences estimator (equation 2) and the effect of political popularity -using difference-indifferences-in-differences estimator (equation 3). It is important to note that the crucial underlying assumption for the validity of our estimation strategy is that in the absence of cross-regional differences in institutional environment (i.e., judicial quality and political popularity of the governor) the growth rates of sales and labor productivity of firms in bankruptcy and not in bankruptcy would have differed by a constant factor conditional on control variables X and would not have been related to judicial quality.

We subtract sample means from each of the variables in all of the interaction terms in order to make interpretation of β 1 straightforward: it is equal to the full effect of reorganization on restructuring evaluated at the mean values of J and P. β 1 in both equations, β 2 in equation ( 2) and β 3 in equation ( 3) are our main parameters of interest. β 2 in equation ( 1) estimates how restructuring in reorganization proceedings depends on judicial quality, whereas, the coefficient on the triple interaction term, β 3 in equation ( 3), estimates whether the latter effect is influenced by the political popularity of the governor.

Error terms are assumed to cluster at the regional level. X i is a vector of control variables, which includes three-digit industry dummies, logs of sales and of employment in 1997, and log change in the stock of the outside finance taken from the firm's balance sheet in 1998-1999. The latter covariate is included to control for a firm's ability to raise outside finance, which is different for firms in and outside bankruptcy and can directly influence their performance. The number of firms that started reorganization procedure in 1998, for which we have all required data, is 115. The resulting sample consists of 319 to 336 firms, depending on the number of missing observations for some covariates.

Table 4 presents the regression results, which are as follows: First, as we have hypothesized, at the mean level of regional characteristics, reorganization procedure has no effect on any of the restructuring measures; namely, there is no difference in restructuring for firms in and outside bankruptcy. (None of the coefficients of the reorganization dummy is statistically significant, and their magnitude is rather small.)

Second, as predicted, judicial quality has an important effect on restructuring in bankruptcy:

firms under reorganization proceedings restructure significantly more that firms outside bankruptcy in regions with a high quality of the judiciary and restructure significantly less in regions with a low quality of the judiciary. The cross-term of reorganization dummy and judicial quality has positive and for two out of the three measures of restructuring statistically significant effect. At the level of judicial quality one half of the standard deviation below the mean, firms under reorganization proceedings have 8% lower growth in sales and 16% lower number of new product varieties compared to similar firms outside bankruptcy. In contrast, at the level of judicial quality one half of the standard deviation above the mean, firms under reorganization proceedings have 8% higher growth in sales and only 4% lower growth in product varieties compared to similar firms outside bankruptcy. Thus, judicial quality is crucial to enforcing restructuring of bankrupt firms.

Third, the coefficient on the triple interaction between reorganization, judicial quality and political popularity of the governors has the right sign and is significant for two out of three measures of restructuring, i.e., sales and productivity growth. Thus, we also find support for our hypothesis that politically powerful governors adversely affected the outcomes of reorganization proceedings in regions with poor judicial quality.

Overall, we found strong support for our main hypotheses.

Conclusion

The application and enforcement of 1998 Bankruptcy Law in Russia vividly demonstrates that commercial court judges were biased in favor of politically popular regional governors.

Reorganization proceedings were significantly more frequent in the regions with politically popular governors and governors who had hostile relations with the federal government. Poor judicial quality was also associated with higher incidence of reorganizations. Moreover, the quality of the regional judiciary affected performance of firms in reorganization: in the regions with poor judicial quality firms in reorganization underperformed relative to firms not in bankruptcy, while the opposite was true for the regions with high-quality judges. This effect is stronger in the regions with popular governors where the bias in governor's favor in courts of poor quality is the strongest.

The political influence of regional governors had transformed bankruptcy into the mechanism that allowed large firms to leave outside claim holders unsatisfied. In particular, the federal government (the largest claim holder on Russian firms) had no effective legal mechanism for collecting tax arrears. The weak and dependent judiciary played a crucial role in this story: The law gave judges substantial discretion over decisions on the fate of insolvent firms (while the rationale was to avoid inefficient liquidations). This discretion was exploited by politically strong regional governors, who had influence over the regional judiciary. Our analysis suggests that it may be J a n -9 3 J u l -9 3 J a n -9 4 J u l -9 4 J a n -9 5 J u l -9 5 J a n -9 6 J u l -9 6 J a n -9 7 J u l -9 7 J a n -9 8 J u l -9 8 J a n -9 9 J u l -9 9 J a n -0 0 J u l -0 0 J a n -0 1 J u l -0 1 J a n -0 2 J u l -0 2

Commercial bank claims on the private sector as percent of quarterly GDP Bank credits and loans of enterprises as percent of quarterly GDP Share of overdue bank credits and loans in total

Figure 1 .

 1 Figure 1. Dynamics of bank credit to firms before and after the enactment of the bankruptcy law of 1998. (Position of vertical axis indicated the date of enactment.)

Figure A1 .

 A1 Figure A1. Non-parametric relationship between regional judicial quality, on the one hand, and governor's hostility towards the federal center and governor's political popularity, on the other hand

1

  Are Russian Commercial Courts Biased? Evidence from a Natural Bankruptcy Experiment * Ariane Lambert-Mogiliansky, Konstantin Sonin, and Ekaterina Zhuravskaya * *

	October 19, 2006

Table 1 .

 1 Initiation of bankruptcy procedures

			Proceedings initiated:
	Year	total	excluding proceeding against
			absent debtors
	1993	<100	n/a
	1994	240	n/a
	1995	1 108	n/a
	1996	2 618	n/a
	1997	4 320	n/a
	1998	8 337	4 893
	1999	10 933	5 940
	2000	19 041	7 959
	2001	56 920	8 538
	Source: Higher Arbitration Court of the Russian Federation

Table 2 .

 2 Firms under different bankruptcy proceedings compared to the population of firms Comparison group is no bankruptcy. Clusters for combination of 2-digit industry and region are allowed. Second column for each outcome reports marginal effects. (Marginal effects for all three outcomes sum to unity.) Marginal effects are evaluated at the mean values of independent variables. Robust standard errors in brackets. * significant at 10%; ** significant at 5%; *** significant at 1%.

		Significant	Firms that fell into	Firms that fell into	Population of
		difference	reorganization	liquidation	firms
		b/w R & L	proceedings in	proceedings in
		at 5% level	1998	1998
			Median	Mean	Median	Mean	Median	Mean
				(SE)		(SE)		(SE)
	Employment (persons),	Y	796	2,027	240	472	143	489
	1997			(202)		(45)		(11)
	Sales (Rb.), 1997	Y	18,471 225,491	3,282	14,620	4,516	44,692
				(50,562)		(4,785)		(3,806)
	Cost per ruble of output	Y	112	143	135	206	97	117
	(Rb.), 1997			(7)		(45)		(0.97)
	Labor productivity	Y	27	58	15	21	37	58
	(Rb./employee), 1997			(6)		(2)		(62)
	Labor productivity	Y	-17	-18	-29	-25	-5	-4
	growth (%), 1996-1997			(2)		(3)		(34)
	Balance sheet net profit	N	-287	-4,349	-297	-3,935	11	3,334
	(Rb.), 1997			(2,042)		(962)		(437)

[START_REF] Berglof | The Formation of Legal Institutions for Bankruptcy: A Comparative Study of the Legislative History[END_REF] note that "the most striking feature of Russian bankruptcy law, and of Russian corporate law in general, is the enormous discrepancy between laws on the book and the laws as they are enforced" (see alsoPistor, Raiser, and Gelfer,

2000).2 In addition, Michelle Camdesus, the Managing Director of the International Monetary Fund, stated in his address at the U.S.-Russia Business Council on April 1, 1998: "A new bankruptcy law entered into effect on March 1 which -though not perfect -should provide a powerful tool for enforcing tax compliance and hard budget constraints."

"Using Bankruptcy As a Takeover Tool: Russian Law Puts Healthy Companies at Risk," New York Times, October 7, 2000.

Available information on bankruptcies in Russia is very limited: we only have access to the lists of firms against which bankruptcy procedures were initiated in 1998 and the first half of 1999. We merge this information to firm-level and regional-level data from other sources. Unfortunately, there are no micro data on who initiated bankruptcy procedures or what the receipts of any of the claim holders were. Therefore, it is important to keep the data limitations in mind during the following discussion of the tests we perform.

Unlike other explanatory variables, J partly is measured after the 1998 law got in force. Yet, bankruptcy cases are a tiny share of all the cases considered in the commercial courts, so we do not expect to have any problem with reverse causality.

worthwhile to give up some sophisticated features of the law, including judges' discretion, in order to secure implementation of its basic objectives. This is in line with the conclusions of the World Bank's Doing Business report (2005), which shows that judicial discretion leads to inferior outcomes in countries with weak institutions.


Andrew E Clark
email: andrew.clark@ens.fr

Andrew J Oswald
email: andrew.oswald@warwick.ac.uk

The curved relationship between subjective well-being and age

Keywords: Happiness, ageing, well-being Happiness, ageing, well-being

. Using a large British data set, the paper presents new longitudinal evidence. It also points out that, perhaps unknown to many psychologists, a parallel literature on this topic exists in economics journals. The paper shows that subjective well-being follows a U-shape through the life course. We argue that eventually the two literatures will have to be made consistent with one another, and suggest that, although it is not easy to live in both worlds, with their different styles and conventions, economists and psychologists still have much to learn from one another.

The Curved Relationship Between Subjective Well-Being and Age

The relationship between happiness and age is important but still imperfectly understood. On page 1336 of an interesting article in this journal, [START_REF] Mroczek | The effect of age on positive and negative affect: A developmental perspective on happiness[END_REF] state that, to their knowledge, "no previous study has considered the possibility of nonlinear relationships between age and happiness." A follow-up study by [START_REF] Mroczek | Change in life satisfaction during adulthood: Findings from the Veterans Affairs Normative Aging study[END_REF] is in the same spirit but uses different methods. The former article finds that positive affect has an upwardly curved component; the latter suggests that subjective well-being follows an inverted U-shape and peaks at around age 60. On our reading of these two papers, they are important work. They are currently acquiring high numbers of citations in the Social Science Citation Index. A literature in psychology journals is growing up around them.

We present new longitudinal evidence on this issue. Its chief finding does not seem to exist in the psychology journals. A second aim of our article is to alert psychologists to a parallel literature on the nonlinear relationship between happiness and age. It is research published mainly in economics journals. This stream of work may have originated from [START_REF] Clark | Unhappiness and unemployment[END_REF]. Using a 12-item measure of psychological well-being, and a cross-section of 6100 randomly sampled Britons from the first wave of the British Household Panel Survey, that paper found mental well-being to be U-shaped in age. The authors' data were for 1991.

The paper drew the conclusion that the happiness minimum along the U is reached around a person's mid-30s.

Since then, a body of work by economists and statisticians has suggested, across a range of settings, that the relationship between subjective well-being and age is curved. Almost every study replicates the basic conclusion: that happiness is U-shaped in age, with a minimum point in a range from the mid-30s to approximately the late-40s. The result has now been demonstrated for perhaps fifty nations. It has been found especially in data from Western countries such as the United States, the United Kingdom, Australia, France, Italy, Belgium, Germany, Spain, and Switzerland.

The U-shape in age is documented in, for example, [START_REF] Gerlach | A paper on unhappiness and unemployment in Germany[END_REF], [START_REF] Oswald | Happiness and economic performance[END_REF], [START_REF] Theodossiou | The effects of low-pay and unemployment on psychological wellbeing: A logistic regression approach[END_REF], [START_REF] Winkelmann | Why are the unemployed so unhappy? Evidence from panel data[END_REF]Winkelmann (1998), Di Tella et al (2001), [START_REF] Frey | Happiness and economics[END_REF], [START_REF] Helliwell | How's life? Combining individual and national variables to explain subjective well-being[END_REF], [START_REF] Blanchflower | Well-being over time in Britain and the USA[END_REF], [START_REF] Graham | Insights on development from the economics of happiness[END_REF], [START_REF] Frijters | Evidence from increasing real income and life satisfaction in East Germany following reunification[END_REF][START_REF] Frijters | The causal effect of income on health: Evidence from German reunification[END_REF], [START_REF] Senik | When information dominates comparison -Learning from Russian subjective panel data[END_REF], [START_REF] Van Praag | Happiness quantified: A satisfaction calculus approach[END_REF] Recently, [START_REF] Blanchflower | Is well-being U-shaped over the life cycle? Unpublished paper[END_REF], using data on approximately half a million Europeans and Americans, argues that allowance for the inclusion of cohort effects makes little difference to the finding of a U-shape.

These papers' methods vary slightly. Nevertheless, each of them, as in the work of [START_REF] Mroczek | The effect of age on positive and negative affect: A developmental perspective on happiness[END_REF], draws upon multiple-regression models. In this way, factors other than age are held constant.

We here report briefly an updated version of the results of [START_REF] Clark | Unhappiness and unemployment[END_REF]. Since

then, the British Household Panel Survey has happened annually, so it is possible to re-do those calculations on a longitudinal data set now exceeding 100,000 observations. A new test can now be done, in which both fixed-effects and age can be allowed for in a multiple regression equation framework.

One variable we use is life satisfaction. It is measured on a seven point scale from 1 (not satisfied at all) to 7 (completely satisfied Responses are made on a four-point scale of frequency of a feeling in relation to a person's usual state: "Not at all", "No more than usual", "Rather more than usual", and "Much more than usual".

The between-item validity of the GHQ-12 is high in the BHPS, with a Cronbach alpha of 0.89. For simplicity, we use the so-called Caseness GHQ score, which counts up the number of questions for which the response is in one of the two "low well-being" categories. This count is then reversed, to convert it into a well-being rather than ill-being score, which thus runs from a possible low of 0 (all twelve responses indicating poor psychological health) to a high of 12 (no responses indicating poor psychological health). The well-being GHQ measure has mean of 10.14 and standard deviation of 2.92.

Life-satisfaction and GHQ measures of subjective well-being seem valuably complementary.

They capture different aspects of affect. However, as we show below, the two exhibit a similar pattern over the life course.

Although the size of the BHPS data set has expanded since the initial research was done, and it is now possible to control for people's unchanging dispositions (fixed effects), the main conclusion remains approximately the same as in the simpler evidence of [START_REF] Clark | Unhappiness and unemployment[END_REF]. Both wellbeing-GHQ and life satisfaction are U-shaped across age groups. In the full longitudinal data set here from 1991 to 2004, it reaches a minimum in the age range 40-49, which is a little later than the early estimate that came out of our single-year of 1991 data.

The coefficients on the other age-bands reveal a fairly smooth curve --down and then up -through the lifespan. This finding is not sensitive to the exact specification of the well-being equations. The pattern in the raw data is illustrated in Figure 1 for the latest wave at our disposal, which is 2004. As is clear from the Figure, it is not necessary to use regression equations to see the approximate U-shape across age-groups.

It is known that many variables shape subjective well-being [START_REF] Diener | Subjective well-being: Three decades of progress[END_REF][START_REF] Easterlin | Explaining happiness[END_REF][START_REF] Lucas | Unemployment alters the set point for life satisfaction[END_REF][START_REF] Gilbert | Stumbling on happiness[END_REF]). If we control in the regression equations for region, year, income, the work status of the individual (ie. whether employee, self-employed, unemployed, retired from work), the number of children, gender, marital status, whether a renter or home-owner, the level of education, and subjective physical health, then, once again, well-being reaches a minimum in the age band 40-49.

For the formal analysis, as say reported using simple methods in Table 1, it makes no substantive difference whether we use logistic regression or simple methods like Ordinary Least Squares (OLS), or random-effects or fixed-effects models. The third column of Table 1 follows the same individuals through time --annually from 1991 to 2004 --whilst holding constant their unchanging fixed-effects, and allowing for many other characteristics such as marital status. By using banded age dummy-variables, in a way that to our knowledge has not been done before in longitudinal work of this sort, in either the psychology or economics literatures, Table 1 provides clear evidence of a U-shape.

Our finding of a U-shape using longitudinal data does not appear to exist in the psychology literature. It is not clear why the results of this economics research literature differ in some significant ways from, say, those in [START_REF] Mroczek | Change in life satisfaction during adulthood: Findings from the Veterans Affairs Normative Aging study[END_REF], which finds almost the reverse --an inverted U-shape in age. It seems important that future work explore these interesting issues more fully. A deeper theoretical understanding of the empirical happinessage curve will also be required.

Psychologists were working on well-being data some decades before researchers in economics [START_REF] Bradburn | The structure of psychological well-being[END_REF][START_REF] Diener | Subjective well-being[END_REF]. We hope, nevertheless, that this short article might be a useful guide to economists' writings on happiness and age.

Over recent decades, economists --including ourselves --have been guilty of not reading the psychology journals sufficiently. Psychologists, similarly, may not have read the economics journals as much as might be ideal. Despite the methodological differences, both sides would, arguably, benefit if we could learn to communicate more effectively. Life Satisfaction GHQ

Figure 1. Mean Life-Satisfaction and Wellbeing-GHQ in British Data. BHPS Wave 14 (2004) Mean Life Satisfaction. BHPS 2004

	5.6
	5.5
	5.4
	5.3
	5.2
	5.1
	5
	4.9
	4.8
	4.7
	16-19	20-29	30-39	40-49	50-59	60-69
		Mean GHQ. BHPS 2004
	10.35
	10.3
	10.25
	10.2
	10.15
	10.1
	10.05
	10
	9.95
	9.9
	9.85
	16-19	20-29	30-39	40-49	50-59	60-69

Table 1 . Well-Being Regressions. BHPS Waves 1-14.

 1 The omitted age band is 16-19 years old. Standard errors in parentheses. * significant at 5%; ** significant at 1%. The controls in columns 2 and 3 are for income, labour force status, number of children, sex, marital status, education, health,and wave and regional dummies.

		No controls	Demographic	Demographic
			controls	controls plus
				Individual Fixed
				Effects
	Age 20-29	-0.154**	-0.230**	-0.161**
		(0.021)	(0.023)	(0.025)
	Age 30-39	-0.224**	-0.380**	-0.170**
		(0.023)	(0.029)	(0.034)
	Age 40-49	-0.315**	-0.487**	-0.187**
		(0.024)	(0.031)	(0.042)
	Age 50-59	-0.155**	-0.334**	-0.165**
		(0.026)	(0.032)	(0.050)
	Age 60-69	0.188**	-0.053	-0.061
		(0.028)	(0.038)	(0.059)
	Constant	5.339**	5.023**	4.938**
		(0.019)	(0.036)	(0.496)
	Observations	90567	87797	87797
	R-squared	0.014	0.146	0.025
		No controls	Demographic	Demographic
			controls	controls plus
				Individual Fixed
				Effects
	Age 20-29	-0.093**	-0.223**	-0.228**
		(0.036)	(0.040)	(0.045)
	Age 30-39	-0.248**	-0.399**	-0.374**
		(0.042)	(0.053)	(0.064)
	Age 40-49	-0.347**	-0.452**	-0.464**
		(0.045)	(0.057)	(0.081)
	Age 50-59	-0.228**	-0.186**	-0.314**
		(0.048)	(0.059)	(0.099)
	Age 60-69	0.157**	0.197**	-0.106
		(0.049)	(0.067)	(0.119)
	Constant	10.265**	9.204**	9.625**
		(0.032)	(0.067)	(1.247)
	Observations	145424	141875	141875
	R-squared	0.003	0.119	0.032
	Notes.

Paris-Jourdan Sciences Economiques (PSE) is a Joint Research The second author's work was funded by an ESRC professorial research fellowship


Automated DTI analysis of MS lesions and their contralateral regions of interest using the mid-sagittal plane as a reference pathology both in the brain and the spinal cord. Studies were performed with histogram analysis of the diffusion characteristics (ADC/FA/MD) in the whole brain or large parts of it [START_REF] Rovaris | Diffusion MRI in multiple sclerosis[END_REF][START_REF] Wilson | Quantitative diffusion weighted magnetic resonance imaging, cerebral atrophy, and disability in multiple sclerosis[END_REF][START_REF] Ciccarelli | Investigation of MS normal-appearing brain using diffusion tensor MRI with clinical correlations[END_REF][START_REF] Nusbaum | Whole-brain diffusion MR histograms differ between MS subtypes[END_REF]. Analysis of semi-automatically delineated regions of interest (ROI) were performed both in MSL and the NAWM [START_REF] Bammer | Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis[END_REF][START_REF] Droogan | Comparison of multiple sclerosis clinical subgroups using navigated spin echo diffusion-weighted imaging[END_REF][START_REF] Filippi | A quantitative study of water diffusion in multiple sclerosis lesions and normal-appearing white matter using echo-planar imaging[END_REF][START_REF] Roychowdhury | Multiple Sclerosis: Comparison of Trace Apparent Diffusion Coefficients with MR Enhancement Pattern of Lesions[END_REF][START_REF] Werring | Diffusion tensor imaging of lesions and normal-appearing white matter in multiple sclerosis[END_REF][START_REF] Castriota-Scanderbeg | Coefficient Dav Is More Sensitive Than Fractional Anisotropy in Monitoring Progression of Irreversible Tissue Damage in Focal Nonactive Multiple Sclerosis Lesions[END_REF][START_REF] Filippi | Diffusion tensor magnetic resonance imaging in multiple sclerosis[END_REF][START_REF] Nusbaum | Regional and Global Changes in Cerebral Diffusion with Normal Aging[END_REF][START_REF] Ranjeva | MRI/MRS of corpus callosum in patients with clinically isolated syndrome suggestive of multiple sclerosis[END_REF][START_REF] Cassol | Diffusion tensor imaging in multiple sclerosis: a tool for monitoring changes in normal-appearing white matter[END_REF]. Overall, in MSL, but also in the NAWM and NAGM, increased values of MD and decreased values of FA/RA were reported. Even if DT-MRI in MS conveys more detailed information about tissue damage than conventional MRI studies it should be kept in mind that DT-MRI shows a good sensitivity to detect diffusion abnormalities and has the potential to exhibit de-or re-myelinisation effect . On the other hand DW-MRI lacks specificity to distinguish between changes in membrane permeability, tissue integrity, gliosis, inflammation or axonal loss. Heterogeneous results of diffusion imaging in MS lesions have been explained by lesion heterogeneity, basically in terms of lesion age, degree of tissue loss and presence or absence of active inflammation on conventional MRI (i.e. Gdenhancement) [START_REF] Bammer | Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis[END_REF][START_REF] Droogan | Comparison of multiple sclerosis clinical subgroups using navigated spin echo diffusion-weighted imaging[END_REF][START_REF] Filippi | A quantitative study of water diffusion in multiple sclerosis lesions and normal-appearing white matter using echo-planar imaging[END_REF][START_REF] Roychowdhury | Multiple Sclerosis: Comparison of Trace Apparent Diffusion Coefficients with MR Enhancement Pattern of Lesions[END_REF][START_REF] Werring | Diffusion tensor imaging of lesions and normal-appearing white matter in multiple sclerosis[END_REF][START_REF] Castriota-Scanderbeg | Coefficient Dav Is More Sensitive Than Fractional Anisotropy in Monitoring Progression of Irreversible Tissue Damage in Focal Nonactive Multiple Sclerosis Lesions[END_REF][START_REF] Filippi | Diffusion tensor magnetic resonance imaging in multiple sclerosis[END_REF][START_REF] Scanderbeg | Demyelinating Plaques in Relapsing-remitting and Secondary-progressive Multiple Sclerosis: Assessment with Diffusion MR Imaging[END_REF]. Correlations between diffusion measures and clinical scales have been rather disappointing, and their correlation is at best moderate [START_REF] Ciccarelli | Investigation of MS normal-appearing brain using diffusion tensor MRI with clinical correlations[END_REF][START_REF] Nusbaum | Whole-brain diffusion MR histograms differ between MS subtypes[END_REF][START_REF] Filippi | Diffusion tensor magnetic resonance imaging in multiple sclerosis[END_REF][START_REF] Scanderbeg | Demyelinating Plaques in Relapsing-remitting and Secondary-progressive Multiple Sclerosis: Assessment with Diffusion MR Imaging[END_REF][START_REF] Cercignani | Intra-voxel and inter-voxel coherence in patients with multiple sclerosis assessed using diffusion tensor MRI[END_REF][START_REF] Cercignani | Mean Diffusivity and Fractional Anisotropy Histograms of Patients with Multiple Sclerosis[END_REF][START_REF] Bozzali | Quantification of Brain Gray Matter Damage in Different MS Phenotypes by Use of Diffusion Tensor MR Imaging[END_REF][START_REF] Rovaris | Assessment of normal-appearing white and gray matter in patients with primary progressive multiple sclerosis: a diffusion-tensor magnetic resonance imaging study[END_REF]. Furthermore, DW-MRI studies in MS suggest that focal MD or FA changes do not correlate with brain atrophy measurements [START_REF] Iannucci | Correlation of Multiple Sclerosis Measures Derived from T2-Weighted, T1-Weighted, Magnetization Transfer, and Diffusion Tensor MR Imaging[END_REF][START_REF] Stefano | MR correlates of cerebral atrophy in patients with multiple sclerosis[END_REF], and moderate correlations were found with ROI histogram analysis [START_REF] Wilson | Quantitative diffusion weighted magnetic resonance imaging, cerebral atrophy, and disability in multiple sclerosis[END_REF].

In this paper, we propose to compare three automated methods of diffusion tensor estimation, and also three automated image distortion corrections for the processing of MR Diffusion Tensor Images (DTI) in patients with multiple sclerosis (MS). Here we propose automated tools for the exact comparison of DTI invariants (fractional anisotropy (FA) and mean diffusivity (MD)) between lesions and their contralateral regions of interest (ROI) in the normal appearing white matter (NAWM).

Methods

A lot of different methods for the estimation of tensors have been proposed in the past few years, but none has been evaluated in a pathological context. As of today most of the studies involving MS and DTI were conducted using standard least squares (LS) estimation of the tensors. This classical method has been shown to have more variation in both trace and orientation of the tensors than the weighted least squares (wLS) or constrained non linear least squares (CNLS) methods [START_REF] Koay | Analytically exact correction scheme for signal extraction from noisy magnitude MR signals[END_REF]. Another very important pre-processing is the correction of eddy current distortion [START_REF] Wiest-Daesslé | Evaluation of a new optimisation algorithm for rigid registration of MRI data[END_REF], and is often either not performed or done using a very simple model. In this paper we compare the effects of distortion correction using linear, polynomial second order and polynomial third order transformations, and no distortion correction on DTI invariants of MSL and their contralateral counterparts. The contralateral ROIs are automatically computed using the mid-sagittal plane as a reference [START_REF] Prima | Computation of the Mid-Sagittal Plane in Diffusion Tensor MR Brain Images[END_REF]. The comparison was performed using ANOVA and multiple comparison procedure in two main groups : 1) MSL and 2) contralateral ROI as well as for each of the combination of pre-processing (12 groups), resulting in 24 entries in our multiple comparisons procedure.

Diffusion tensor estimation

In order to exploit the information included in diffusion-weighted MRI (DW-MRI) a model of the diffusion is required. The first proposed model that can provide information on the fiber orientation is the tensor model of the diffusion. This model is the simplest available one for the diffusion in order to include fiber orientation and is the most often used model in the clinical context. A tensor is mathematically represented by a 3 × 3 matrix, which is symmetric and definite positive (SDP), this reflects the physical meaning that the diffusion in a direction can neither be negative nor null. The computation of a tensor is based on the Stejskal-Tanner equation, S i = S 0 e -bDi , which links each image point, voxel, of a diffusion unweighted image S 0 to the spatially corresponding voxels in the diffusion-weighted images S i with the diffusion coefficient D i dependant on the acquisition parameter b. The previous equation is written for each diffusionweighted image with gradient g i using tensors as S i = S 0 e -bg T i Dg T i where D is a tensor. The diffusion tensor being a symmetric matrix only six coefficients need to be computed. This is the reason for the acquisition of a number of diffusion weighted images equal at least to six.

In a paper reviewing the tensor estimation techniques Koay et al. [START_REF] Koay | A unifying theoretical and algorithmic framework for least squares methods of estimation in diffusion tensor imaging[END_REF] showed that this estimation can result in quite different tensors in terms of orientation and shape. The most interesting result of this paper is that the constrained non linear least square has been shown to have the lower relative error in estimating the MD and FA than other methods [START_REF] Koay | Analytically exact correction scheme for signal extraction from noisy magnitude MR signals[END_REF][START_REF] Koay | A unifying theoretical and algorithmic framework for least squares methods of estimation in diffusion tensor imaging[END_REF]. In most DTI and MS related papers the estimation if performed using simple linear least squares (LS) estimation or weighted least squares (wLS). We propose to compare these two methods

MIAMS'08

MICCAI workshop on "Medical Image Analysis on Multiple Sclerosis (validation and methodological issues)"

(LS,wLS) and CNLS (the best one according to Koay et al.) in order to measure the impact of such techniques.

Correction of distortions

DT-MRI consists in acquiring one diffusion-unweighted image and several diffusionweighted images with non-collinear direction-encoding gradients. The tensor summarising the diffusion information is then computed on a voxel-by-voxel basis. Echo Planar Imaging (EPI) is generally used for the acquisition of DW-MRI data. This fast technique reduces the effects due to the subject's motion, but is especially sensitive to eddy currents. These induce geometrical distortions that cause misregistration of the MRI data and thus inaccuracy of the reconstructed tensor. We use different models for the transformation due to the distortions:

-An Affine model (12 parameters) -Two global polynomial models with polynomials of order 2 and 3 (30 and 60 parameters).

Mid-Sagittal Plane (MSP) computation

We propose a method for the automated computation of the mid-sagittal plane (MSP) of the brain in diffusion tensor MR images. We estimate this plane as the one that best superposes the two hemispheres of the brain by reflection symmetry [START_REF] Wiest-Daesslé | Validation of a new optimisation algorithm for registration tasks in medical imaging[END_REF]. This is done via the automated minimization of a correlationtype global criterion over the tensor image which computes the plane parameters.

The MSL are then flipped with respect to the MSP, giving contralateral ROI located in the NAWM.

Experiments

The data are acquired using axial (2 mm slice thickness) DW-MRIs on a 3T (Philips) with 15 directions. The database was constituted with five patients with MS and five control subjects (sex-and age-matched). Conventional DT-MRI tools were applied for the computation of DTI invariants (FA and MD maps). The diffusion tensors were calculated using the LS, wLS and CNLS methods and four methods for the corrections of distortions were applied to the DW-MRI (no correction, affine and the two polynomial models). For controls, the mask of lesions from the MS patients were automatically aligned with the images of the controls, using a linear registration method [START_REF] Wiest-Daesslé | Evaluation of a new optimisation algorithm for rigid registration of MRI data[END_REF].

The lesion mask and contralateral mask of lesion were then used to extract paired-data on the FA and MD maps for each MS patient and control. An analysis of variance (ANOVA) combined with a multiple comparison procedure is then applied to the FA and MD data from each ROI. The ANOVA is fed with voxel data intensity, grouped by ROI: 1) MSL, 2) contralateral MSL ROI, 3) control ROI, 4) control contralateral ROI and by preprocessing. The Figure 1 and 2 show the multiple comparisons procedure output. These Figures has the controls and MS patients displayed as two groups, for this two groups the pre-processing are ordered as follow:

correction of distortion with affine model

• tensor estimation with WLS for the lesion and contralateral ROI • tensor estimation with LS for the lesion and contralateral ROI • tensor estimation with CNLS for the lesion and contralateral ROI correction of distortion with polynomial second order model

• tensor estimation with WLS for the lesion and contralateral ROI • tensor estimation with LS for the lesion and contralateral ROI • tensor estimation with CNLS for the lesion and contralateral ROI correction of distortion with polynomial third order model

• tensor estimation with WLS for the lesion and contralateral ROI • tensor estimation with LS for the lesion and contralateral ROI • tensor estimation with CNLS for the lesion and contralateral ROI no correction of distortions

• tensor estimation with WLS for the lesion and contralateral ROI • tensor estimation with LS for the lesion and contralateral ROI • tensor estimation with CNLS for the lesion and contralateral ROI

In our experiments, whatever processing was applied, three statistically different groups appear on the FA (Fig. 1):

-MSL in MS patients -Contralateral of MSL in MS patients -Controls (both "lesion" and contralateral ROI).

On the FA maps of controls, a slight difference appears depending on the applied processing. On average, this is mainly due to the higher anisotropy in the controls data. The differences in the tensor estimation techniques are clearer in regions of high anisotropy, which is reflected by our experiments. The correction of distortions does not seem to yield specifically different results. For the MD, no statistically different results appear (Fig. 1) but a small variation still exists on two of the preprocessings.

Results

In MS patients a statistical difference between lesions and their contralateral counterparts was found for the FA (but not for the MD), irrespective of the automated image processing methods used. In controls, no statistical difference between ROI associated with MS patient lesions and contralateral ROI was found.

Conclusion

In comparison with widely used manual or semi-automated DTI analysis methodology, in this pilot study with MS patients and age-and sex-matched controls, we show with our automated approach using the mid-sagittal plane as a reference that we were able to replicate results from the literature. Automated image analysis approaches, however, have the advantage being more accurate, reproducible and robust. A statistical difference between MSL and their contra lateral ROI is confirmed as shown in the literature, which does not exists for controls. A statistical difference is present when comparing the three tissues classes from MS patients and controls: 1) MSL ROI, 2) contralateral ROI MSL and 3) controls ROI. Even if the pre processing seems to impact little on statistical differences of the DTI measures in healthy volunteers and MS patients our fully automated approach is superior to manual or semi-automated DT-MRI analyses regarding the robustness of the results (reproducibility and accuracy).

Fig. 1 .

 1 Fig. 1. Multiple Comparison procedure results on FA Maps

Fig. 2 .

 2 Fig. 2. Multiple Comparison procedure results on MD Maps

MIAMS'08MICCAI workshop on "Medical Image Analysis on Multiple Sclerosis (validation and methodological issues)"


Vincent Daien

MD Karine Peres

PhD Max Villain

PhD Alain Colvez

Cécile Delcourt

PhD Isabelle Carriere
email: isabelle.carriere@inserm.fr

PhD Isabelle Carrière

Visual impairment, optical correction and their impact on activity limitations in the elderly. The POLA Study

Keywords: living, Refractive Errors, Elderly

2

The loss of autonomy among older persons is a major public health issue.

In the disablement process model 1 chronic and acute conditions lead to psychological and physical deficiencies and ultimately to difficulty performing activities of daily life. In elderly, visual impairment is one of the major deficiencies leading to activity limitations and can be caused by either eye trauma or ocular diseases (affecting the ability to receive or process visual information), or by refractive errors (a failure of the eye to focus images sharply on the retina). Refractive errors affect about a third of the US and Western European populations. [START_REF] Kempen | The prevalence of refractive errors among adults in the United States, Western Europe, and Australia[END_REF] We estimated the proportion of uncorrected refractive errors and the potential improvement in daily life functioning that could be brought about by optimal visual correction.

Methods. The POLA Study, described in detail previously, [START_REF] Delcourt | Smoking and age-related macular degeneration. The POLA Study. Pathologies Oculaires Liees a l'Age[END_REF] aimed to identify risk factors for age-related eye diseases. The present study concerns the 1947 persons aged 63 years and over who completed the 3-year follow-up (1998 to 2000). Participants were administered standardized questionnaires and were assessed for Instrumental Activities of Daily Living (IADL) limitations [START_REF] Lawton | Assessment of older people: self-maintaining and instrumental activities of daily living[END_REF] (participants unable to perform without assistance at least one of the eight activities of the Lawton scale). Eye examinations, performed by five ophthalmologists in a mobile unit equipped with ophthalmologic devices, included a measure of distance visual acuity in each eye with their usual optical correction (or no correction if they did not wear glasses/contact lenses) and then with the best achieved correction determined using objective refraction (RM-A7000, Topcon, Japan) and lenses of varying power.

Distance visual acuity was assessed with the Snellen decimal chart and analysed by extending

the World Health Organization taxonomy of visual impairment. "Low vision" (including blindness) and "Moderate visual impairment" were defined as visual acuity in the better eye lower than 6/18 and 6/18 to 6/12, respectively. The "unilateral visual loss group" included inserm-00590426, version 1 -3 May 2011 participants with visual acuity worse than 6/12 for one eye and normal for the other eye and the "normal group" those with 6/6 to 6/12 in each eye.

To assess the proportion of IADL-limitations that could be prevented with the use of the best achieved correction, the generalized impact fraction (GIF) of inappropriate optical correction was estimated using equations previously described [START_REF] Loehr | The potentially modifiable burden of incident heart failure due to obesity: the atherosclerosis risk in communities study[END_REF] and stratified by age group (63 to 74 versus 75+). The age-stratified GIFs were combined using a case-load weighed sum method for an overall GIF. [START_REF] Benichou | A review of adjusted estimators of attributable risk[END_REF] The 95% Confidence Interval (CI) was obtained by bootstrapping.

Results. Of the 1947 participants 3.0% were excluded due to missing data, leaving 1887 participants (804 men and 1083 women) for this analysis. The median age was 72.3 years (interquartile range 68.1-77.0) and 10.3% (195) had IADL-limitations.

Moderate visual impairment and low vision were much more frequent in subjects with IADLlimitations (39.0% versus 23.3 % and 24.1% versus 5.6%, respectively) but not unilateral visual loss. Overall, 38.5% of participants had an inappropriate optical correction, which accounted for 64.5% and 50.4% of the cases of moderate visual impairment and low vision, respectively.

The overall GIF which represents the fractional reduction of activity limitations resulting from changing the usual visual correction to the best achieved visual correction (Table ) was estimated to 20.5% (95% CI, 13.6-27.9). We were not able to adjust the GIF calculation for all possible confounders because of sparse data; 6 however age was the only obvious confounding factor when we examined the association between vision and activity limitations (adjusting for gender, living alone, smoking, alcohol, body mass index, cardiovascular and cerebrovascular disease, antidepressant use, and hospitalization).

Comment. Among this non-institutionalized elderly population the majority of cases of low vision and moderate visual impairment were due to uncorrected refractive errors. One fifth of inserm-00590426, version 1 -3 May 2011 IADL-limitations could be prevented by use of the best optical correction. Our results underline the importance of including eye examinations in cohorts studying disability and integrating ophthalmic surveillance in routine evaluation of the elderly.

According to the 2009 American Academy of Ophthalmology recommendations, people aged over 65 should have eye examinations every one to two years. This is critical to not only detect eye diseases but to measure refractive errors (which vary with age) and to correct these with glasses or contact lens. Programs designed to provide optical services in this population may contribute to maintaining activities and autonomy in elderly.

Financial Disclosure:

  None reported

Table .

 . Number and percent of subjects having distance vision loss with usual and best achieved optical correction (N=1887).

				Best achieved optical correction
		Usual optical correction	Normal	Unilateral	Moderate	Low vision	Total
			bilateral	visual loss	visual
					impairment
		Normal bilateral	726 (38.5)	-	-	-	726 (38.5)
		Unilateral visual loss	353 (18.7)	197(10.4)	-	-	550 (29.1)
		Moderate visual impairment	187 (9.9)	116 (6.1)	167 (8.9)	-	470 (24.9)
	inserm-00590426, version 1 -3 May 2011	Low vision Total	22 (1.2) 1288 (68.3)	18 (1.0) 331 (17.5)	31 (1.6) 198 (10.5)	70 (3.7) 70 (3.7)	141 (7.5) 1887 (100)

Funding/ Support: : This study was supported by the Institut National de la Santé et de la Recherche Médicale, Paris, France; by grants from the Fondation de France, Department of Epidemiology of Ageing, Paris, the Fondation pour la Recherche Médicale, Paris, the Région Languedoc-Roussillon, Montpellier, France and the Association Retina-France, Toulouse; and by financial support from Rhônes Poulenc, Essilor, Specia and Horiba ABX Montpellier, and the Centre de Recherche et d'Information Nutritionnelle, Paris. These sponsors funded the preparation of the POLA study and the data collection.

Data access: Cecile Delcourt and Isabelle Carrière have full access to all of the data in the study and take responsibilityy for the integrity of the data and the accuracy of the data analysis.