Jean-Luc Ga¤ard

Francesco Saraceno
email: francesco.saraceno@sciences-po.fr

Cuong Le Van

International Trade and Domestic Distortions: Modelling the Transition Process

Keywords: F11, F12, F42, F43 globalization, trade, …nancial constraints, creative destruction, wage ‡exibility, time to build, Firm migration

According to the standard view, when full competition prevails in product, labour, and capital markets, positive or negative external trade shocks may be accommodated by the migration of jobs between sectors; the negative impact on some households' income of lower nominal wages will be more than o¤set by lower prices of imported …nal goods. Unemployment, if any, will be temporary, unless labour market rigidities prevent the necessary adjustment. We argue that trade shocks trigger a process of creative destruction that necessarily causes distortions in the structure of productive capacity and hence market disequilibria. Therefore, the structural change that follows trade shocks can no longer be analysed within an equilibrium framework. The transition following a shock may be characterized by increasing imbalances, and create scope for policy intervention. The model presented in this paper, which focuses on the time dimension of production and market imbalances, allows clarifying the debate.

Introduction

Developed economies exposed to competition from large emerging countries such as China or India experience signi…cant increases of imports, relocation, outsourcing and jobs'destruction in manufacturing sectors but also in valueadded services, which are becoming tradable. Emerging countries are exposed to a symmetric shock: an increase of exports and FDI that implies deep changes in industrial organisation and hurts the workers. International order is deeply disturbed. This feeds a recurrent debate between the tenants of the free market and those who plead for increasing protection.

According to the elementary theory of international trade, which rests on the law of comparative advantages, an increase of exchanges between countries is systematically bene…cial to all partners. Importing new goods and services, even when these goods were previously domestically produced, creates new opportunities and allows using productive resources in a different and more e¢ cient way. The loss of manufacturing jobs due to the growing import penetration is generally o¤set by the job creation e¤ect of growing exports. Penetrating international markets by exporting new goods and services purchased by the consumers of more advanced countries allows emerging countries to take advantage of larger productivity gains associated with export sectors (Lucas 1993). International trade is thus a positive sum game and cannot be considered as responsible of increasing unemployment, waste of resources, and lower growth in any country.

However, old as well as more recent analyses demonstrated the possibility of losses for some participants to the exchange. These losses would be essentially due to di¤erences in productivity gains among countries, which result in di¤erences in real income [START_REF] Hicks | An Inaugural Lecture[END_REF][START_REF] Krugman | A Technology Gap Model of International Trade[END_REF][START_REF] Gomory | Global Trade and Con ‡icting National Interests[END_REF][START_REF] Samuelson | Where Ricardo and Mill Rebut and Con…rm Arguments of Mainstream Economists Supporting Globalization[END_REF]). These models deal with the welfare e¤ects for a country when domestic production is taken over by its trading partner, generally a less advanced country. [START_REF] Krugman | A Technology Gap Model of International Trade[END_REF] argues that while technical progress in the more advanced country is always bene…cial to both countries, progress in the poorest country can, depending on circumstances, be harmful for the more advanced one. Similarly, [START_REF] Gomory | Global Trade and Con ‡icting National Interests[END_REF] show that with increasing returns, and for su¢ ciently close levels of income in the two countries, trade and relocation will harm the rich country. There are many possible outcomes ranked in terms of welfare. Thus when a new outcome corresponding to a di¤erent distribution of industries among countries prevails, there will be winners and losers.

This paper is not concerned by the …nal welfare e¤ects of changing trading patterns. We focus on the complementary issue of the adjustment that has to take place following the trade shock. One cannot deny that changes in international trade entail social and distributional costs. "Trade can generate sizable bene…ts only by restructuring economies -that is the essence of specialization according to comparative advantage -and in the real world restructuring does not happen without someone bearing costs. The ‡ip side of the gains from trade is the losses that have to be incurred by adversely affected workers and enterprises(. . . ). Simply put: no pain, no gain. It makes little sense to pretend otherwise" (Rodrik, 1998 p. 5). Thus it is not enough to focus on the distribution of gains between countries or within countries (among di¤erent skills, or between wages and pro…ts). In the following we will argue forcefully restructuring is an intrinsic feature of globalization and relocation processes; in fact, increasing openness is a form of structural change and hence analytically equivalent to technical progress; as such, it entails the destruction of the existing productive capacity (and of the corresponding jobs), and the construction of something new to replace it. Thus, distortions are not an impediment to a smooth transition to the new equilibrium, as argued by the tenants of free market paradigm; they are an intrinsic and unavoidable feature of the structural change process. We push Rodrik's argument even farther, by arguing that this process of restructuring needs not to be successful: the ex ante bene…ts from increased openness may ex post fail to materialise, if something goes wrong with the co-ordination process. Thus, the process of restructuring needs not to be successful.

Our medium-run analysis on the conditions for the success of the transition will be, inevitably, concerned with short-term e¤ects on employment and wages and hence with policy conclusions. In fact, we will conclude that the viability of the transition, and the recovery of coordination crucially hinge upon the right mix of institutional and policy factors, notably in what concerns access to credit.

The remainder of this paper is structured as follows: section 2 contrasting the standard neoclassical framework with an evolutionary one, is an attempt to identify which domestic distortions matter in a country facing a change in conditions of international competition. Sections 3 and 4 then propose a model that allows both reproducing neoclassical results and introducing an analytical framework suited to deal with structural change. By using the model and simulating out-of-equilibrium paths, section 5 shows how real domestic distortions in ‡uence the evolution of the economy, and hence why and how international trade matters. Section 6 concludes.

Which Domestic Distortions Matter?

Changes in international trade will result in mutual gains if there is no obstacle to prevent the redistribution of productive resources among sectors that allows the convergence toward the full employment equilibrium. Thus, the low-wage country will be able to use an a-uent amount of labour in the production of new goods. The high-wage country will be able to increase productivity, by reallocating its labour force in the value-added services and high-tech sectors, where it has a comparative advantage. It will also be able to shift some workers from manufacturing to service jobs even if the latter require lower skill and hence involve lower nominal wages (compensated by the decrease of prices of imported goods).

Within the standard analytical framework these considerations lead to focus on the role played by wage adjustments and distortions associated with them. For the gains from trade and relocation to occur it is essential that no domestic distortion prevents the necessary adjustment (i.e. the convergence towards the full employment equilibrium). Changes in fundamentals (technology and preferences) must be accommodated by relative prices (in particular wages). In this case, relocation only corresponds to a better allocation of resources at the international level without harmful consequences on employment. Increasing imports will be matched by increasing exports.

The only obstacle that would prevent from capturing the gains from trade is the downward rigidity of wages paid to low-skilled workers. On the one hand, this stickiness would cause unemployment of low-skilled workers. On the other hand, the ‡ows of international trade can be distorted. As [START_REF] Brecher | Minimum Wage Rates and the Pure Theory of International Trade[END_REF] put it, if minimum wage applies in the high-wage and capital abundant country, the labour intensive sector both …res too many workers and sets free a too large amount of capital. As a consequence, both exports of capital-intensive goods and imports of labour-intensive goods grow beyond what is considered their optimal size. This view is coherent with policies that focus on supply conditions with the objectives of increasing competitive advantages for an economy with respect to its external competitors. Reducing wage di¤erentials, improving labour market ‡exibility, reducing taxes seem to be the only viable policies aimed at avoiding domestic distortions and their e¤ects on the structure of international trade, thus favouring full employment. This view is partial, focusing on the functioning of the labour market and ignoring the systemic nature of the process of change and its time dimension. There is no reference to the creation of resources. Price and wage distortions, when occurring, only a¤ect the rate of utilisation of productive resources (labour), and result in their under-utilisation. This is the reason why policy makers have o correct these distortions by reducing direct and indirect labour costs.

This paper takes the view that distortions are intrinsically built in structural change processes, as the one stirred by globalisation. As a matter of fact, economies hurt by changes in international trade are concerned with other distortions that those which are created by the wage stickiness. Changes in international trade go hand-to-hand with the breaking-up in the pre-existing industrial and spatial structure of productive capacity, which results in unavoidable disequilibria between supply and demand of …nal goods, all along the transition towards the new adapted structure of the economy. Thus, the supply side, and in particular investment, become crucial for an analysis of the transition to a new steady state. As the problem does not consist in the reallocation of existing resources but in the creation of a new productive capacity, it is pointless (and may be harmful) to try to bypass the transition and the associate turbulence by eliminating the price distortions. Policy should rather accompany the process of change, progressively removing or softening the constraint faced by the economy.

Indeed, as a consequence of trade liberalization, imports are substituted for goods locally produced, while local exporters have not automatically the necessary supply capacity to expand. Thus, "liberalization seems to result in labour temporarily going from low-productivity protected sectors to zeroproductivity unemployment" (Stiglitz and Charlton 2006 p. 26). This is true both for developing and developed countries. This leads to a reduction of income, and hence in the demand for …nal output, which will be more or less pronounced whether according to the level of social insurances. At the opposite of the conclusion of standard analysis, a high level of social protection can help to avoid global damages associated with a cumulative process of depression.

In this perspective, international trade as well as foreign direct investment matter, but not only with respect to initial endowments or existing externalities. In fact, for an open economy, balanced growth results from harmonisation of external and internal demand with the productive capacity. Trade and openness may be very important factors both in increasing the long-run growth potential, and in smoothing ‡uctuations due to country speci…c shocks; but this positive role is ful…lled only if the economy has internal resources -the reference is mainly to productive capacity, but also to a su¢ cient level of revenues -to match the increase in demand and to keep the balance that is necessary to successfully complete a transition process.

Thus, openness and the emergence of new countries do not create di¢ culties per se. Market disequilibria and distortions in the productive capacity that necessarily emerge both in the emerging and developed countries call for local co-ordination of economic activities, which cannot amount to re-ducing production costs in the hope of re-establishing competitiveness. Coordination should consist in creating the conditions for …rms to deal with these real distortions, which are the unavoidable consequence of structural change.

Summing-up, what is at stake is not to prevent real domestic distortions that are inherent to the process of change, but how to smooth them thanks to appropriate policies. Thus we need a model that puts into light these distortions and allows identifying the required remedies.

The Benchmark Model

We consider a model with one country and two goods. This model does not directly address issues related to growth and trade relationships, but it is an attempt to analyze how an external shock due to an increase in competitiveness of a foreign country a¤ect the composition of goods produced in both countries, and hence global performance.

Our economy is comprised of N …rms, that are divided in the production of a basic (b) and an advanced (a) good. This production is sold to a representative domestic household, who supplies labour inelastically, and to a foreign household. The utility of the domestic household also includes an imported good, and is written as follows:

max u = X a X (1 ) b Z 1 s:t: R = p a X a + p b X b + qZ
where p a ; p b and q are the prices of the advanced, basic and imported good, respectively, and R are total revenues of the household. The foreign household demands W j (j = a; b), that we treat as exogenous. As a consequence, the value of total demand, for the two goods is given by:

p a X a = R + W a (1) p b X b = (1 )R + W b
Demand for the imported good, qZ = (1 )R; does not concern us. The and (with + N ) …rms in the two sectors compete in quantities, à la Cournot. We further assume that workers can work in any of the two sectors (i.e., that w a = w b = w), and that A j is the number of workers per unit produced in each sector j = a; b (we assume constant returns to scale).

The standard, solution of the problem gives

x a = ( 1) ( R + W a ) 2 A a w ; p a = wA a 1 ; = ( R + W a ) 2 (2a) x b = ( 1) ( (1 )R + W b ) 2 A b w ; p b = wA b 1 ; b = (1 )R + W b 2 (2b)
where of course we assume symmetry (x a = X a = , and

x b = X b = ):
To close the model, we …nally assume that pro…ts are distributed to the domestic household, so that household income R is equivalent to the revenues from sales of the two goods produced at home:

R = p a X a + p b X b (3)
From eqs. 3 and 1 we can obtain

R = R + (1 )R + W = W 1 where W W a + W b :
The total revenues of the system are a function of external wealth. As a consequence, from eq. 1 we can de…ne the value of production in the two sectors as

a = p a X a = 1 W + W a = 1 W b + + (1 ) 1 W a b = p b X b = (1 ) 1 W + W b = 1 1 W b + (1 ) 1 W a
Notice that external demand of both goods enters into the two demand curves. This happens through the revenues e¤ect

Equilibrium

The equilibrium relies on two conditions.

The …rst is the equilibrium in the labour market, requiring that the quantity of labour L; inelastically supplied, be equal to labour demand:

L = A b X b + A a X a = A b b p b + A a a p a (4)
The second equilibrium condition is the equality of pro…ts across sectors, which implies that no …rm will have incentive to switch. Rewriting eqs. 2 as

x a = 1 2 A a w a ; p a = wA a 1 ; = a 2 (5a) x b = 1 2 A b w b ; p b = wA b 1 ; b = b 2 ; (5b) the condition a = b yields a 2 = b 2 (6)
Putting together eqs. 4 and 6, using the price equations of eq. 5 and the fact that = N , equilibrium is de…ned by the solution to the following system:

p a = p b N (7a) wL = (N 1) b N + ( 1) a ; (7b)
where the unknowns are and w: The system can be solved recursively to obtain and w

= N p a p b + p a : (8a) w = ( b + a )(N 1) p b a 2 b a LN p b a (8b)
It is interesting to notice that only external demand and the number of …rms help determine and w . Because we de…ne equilibrium through the equality of pro…ts in the two sectors, the technology parameters do not a¤ect the distribution of …rms, nor the wage. We'll see in the next section that these parameters become crucial when analyzing disequilibrium paths. Notice also that, as ( b + a ) 2 p b a > 0; the wage is always positive. On the other hand, equation 8a gives conditions on the parameter for the equilibrium to be meaningful

1 < = N p a p b + p a < N:
The second inequality is certainly veri…ed, while the …rst implies, with some manipulation, 1) :

> 1 () W a W > 1 (1 + (N 1) 2 ) (1 + (N 1) 2 ) (
If external demand for the advanced sector is not large enough, the equilibrium number of …rms may be lower than 1.

Reaction to Shocks

Using equations 8a and 8b, and the fact that d dW j = @ @ b @ b @W j + @ @ a @ a @W j ; we can write

d dW b = p b p a p a p b (1 ) N 2 p b + p a 2 (1 ) ! d dW a = p b p a (1 + ) p a p b ( ) N 2 p b + p a 2 (1 )

!

We are now able to prove a number of propositions:

Proposition 1 d dWa > 0 and d dW b < 0: An increase of external demand for a sector yields a larger equilibrium number of …rms in that sector.

Proof. d dWa > 0 : p b p a (1 + ) p a p b (1 ) ! > 0
() b (1 + ) a (1 ) > 0
Substituting:

((1 ) W b + (1 ) W a ) (1 + ) ( ) ( W b + (1 (1 )) W a ) = W b (1 ) > 0 d dW b < 0 : p b p a p a p b (1 ) ! < 0 () ( b a (1 )) < 0
Substituting:

((1 ) W b + (1 ) W a ) (1 ) ( W b + (1 (1 )) W a ) = ( 1)W a < 0
Proposition 2 d a dWa > 0 and d a dW b > 0: An increase in external demand for any sector yields a larger equilibrium pro…t.

Proof. Equilibrium pro…t can be de…ned, from eqs. 6 and 8a:

a (= b ) = a 2 = p b + p a 2 N 2
As a and j are positively a¤ected by both W a and W b ; we conclude that any increase in external demand increases equilibrium pro…ts

The reaction of wages to external demand shocks is harder to sign, because in fact it depends on the size of the reallocation of workers between the two sectors.

@w @W a = p b a (N 1) ( (1 ) a + (1 + ) b ) LN p b a (1 ) @w @W b = p b a (N 1) ((1 ) a + b ) LN p b a (1 )
Once studied the steady state properties of our model, we can introduce the dynamic elements that essentially involve capacity building and expectations, in the spirit of [START_REF] Amendola | Out of Equilibrium[END_REF]. The model will extend to a two sector Cournot economy the paper by [START_REF] Saraceno | Wage regimes, Accumulation, and Finance Constraints: Keynesian Unemployment Revisited[END_REF].

Adding a Time Structure

Section 2 argued that trade shocks are analytically equivalent to productivity shocks in that they trigger a structural change with the associated distortions that have to be managed for the transition to be successful. To model structural change in a production economy, four ingredients are required: First, Production takes time, and is often characterized by complementarity rather than substitutability in the factors. This is captured analytically by assuming a Leontief production function that uses labour inputted at di¤erent times. Second, agents have bounded rationality, especially when facing complex environments. Thus, expectations are adaptive. Third, no variable may move instantaneously. As in temporary equilibrium models [START_REF] Hicks | Value and Capital[END_REF][START_REF] Benassy | The Economics of Market Disequilibrium[END_REF], prices only adjust between periods; ex-ante disequilibria within the period are eliminated by rationing and stock accumulation. Fourth, agents are constrained, in their transactions, by …nancial availability. This sort of credit or cash-in-advance constraint emerges because markets open sequentially.

The Sequence

Each period begins with some state variables inherited from the previous one. First, labour embedded in production processes (as will be clear below); then, stocks that result from past disequilibria. And …nally, the prices and wages.

Within the period we introduce a sequence that helps in de…ning the time structure of the model.

Prices and wages change in response to market disequilibria, even if we do not let them clear markets.

Firms may also change sector, based on realized pro…ts in the previous period.

Then, after agents form inter and intra period expectations, and accordingly desired demands and supplies. In particular …rms form a demand for labour, and a demand for …nancial means (the wage fund)

The …rst market that opens is the …nancial market, in which demand for external funds may or may not be satis…ed. Financial constraints cause a rescaling of labour demand.

Total labour employed is determined once the second market, the labour market opens. Then wages are paid, and production is carried over.

Households adjust their desired demands based on the actual wage perceived.

Finally, the product market opens, and as in the other markets, the short side rule applies.

The next sections will detail this sequence.

Wage Dynamics

Wages change early in the period, following previous disequilibria:

w t = w t 1 1 + ! L d t 1 L s t 1 L s t 1
Thus ! is an indicator of price ‡exibility; as the equation clari…es, this has nothing to do with market clearing behaviour.

Firm Dynamics

Firms may change sector of activity. This happens when pro…ts di¤er:

t = t 1 1 + a;t 1 b;t 1 a;t 1 + b;t 1 I a
where I a is an indicator function taking a value of 1 only if n 2 (1; N ). Firms changing sector still use the built productive capacity to carry on production in the original sector, but invest in the other sector.

Expectations

Previous work [START_REF] Amendola | Out of Equilibrium[END_REF][START_REF] Saraceno | Wage regimes, Accumulation, and Finance Constraints: Keynesian Unemployment Revisited[END_REF] has explored the role of expectations in this type of models. We could show rather robustly that when interacting with sunk costs and irreversibilities in the production process, adaptive expectations play an important role. We also argued at length that in a complex environment, when collecting complete information may be impossible or extremely costly, agents may …nd it more convenient to follow an adaptive rule. Long term expectations, that drive investment decisions, are instead more independent of contingent conditions. Coherently with these arguments, in this paper we make di¤erent assumptions regarding assumptions: short term or intraperiod expectations are backward looking. Firms decide how much they wish to produce in the current period, based on their expectation of current demand, that in turn is determined by the expected level of employment. The latter is determined as an average between past employment and its "normal" value

L e t = L t 1 + (1 )L
where L = L is the steady state level of employment.

If we are not at full employment, we have to write expected revenues as the sum of paid wages, plus distributed pro…ts

R e t = w t L e t + t 1 + H h t 1
where = a + b : Notice that we add an additional term (H h ): if households had been left with unspent money balances in the previous period, these balances will concur to form current revenues. Expected demand then becomes

x e a;t = t 1 1 2 t 1 A a w t ( R e t + W a;t ) x e b;t = t 1 1 2 t 1 A b w t ( (1 )R e t + W b;t )
It is important to remark that agents take into account the fact that …rms having switched sector do not possess productive capacity (otherwise, t and t would have been used instead of t 1 and t 1 ); we assume in other words that agents use all the information they possess, in order to be as close as possibly allowed, in this context, to rational expectations. The amount …rms will actually attempt to produce, depends also on stocks of goods left from disequilibria from past periods, that the …rm is able to bring back on the market. s e j;t = x e j;t o j;t 1

Finally, interperiod expectations, are important to determine how much to invest, i.e. how many workers to hire today to put in place tomorrow's production. We assume that these decisions are not in ‡uenced by short term movements:

L e t+1 = L = L

Production and Labour Demand

The two elements of complementarity and time-to-build are introduced by assuming that the production function takes the form of a Leontief function with dated labour input s j;t = min[ j l j;t 1 ; j l j;t ] where j = a; b denotes the sector. Thus, dated and current labour concur in …xed proportions to the determination of production; this formulation is equivalent at assuming production to be undertaken with capital built in the previous period, that fully depreciates. Thus, current production is constrained among other things by past "investment". If …rms don't possess the appropriate amount of capital/dated labour, they will not be able to produce as much as they wish. As a consequence, …rms will only demand the labour they really need:

l j;t = 1 j
min s e j;t ; j l j;t 1 :

Labour demand is hence given by Demand for external funds comes from whatever of the wage bill is not covered by past pro…ts. Money demand may then be written as the di¤erence between the wage fund and internal resources.

L d t =
F d t;j = w t L d t;j (S t 1;j + H f t 1;j t 1;j ) ( 9
)
where S is the value of past sales in the two sectors, and H f denotes involuntary monetary hoardings by …rms. Equation 9 embeds the credit constraint: the …rm system needs additional funds for whatever of the wage pool it cannot …nance out of internal resources. As pro…ts are distributed to households at the end of the period, they are not available for …rms. The behavior of the supply side in the …nancial market is not explicitly modeled. In fact, we adopt a very stylized representation, in which the supply of external funds can be interpreted as credit made available by the …nancial sector. We simply assume that the supply of credit by …nancial sector is adversely a¤ected by turbulent times (proxied in our model by the variability of pro…ts), and by the strength of the economy, proxied by the unemployment rate):

F s t;j = max 0; F d t;j (1 )(V ar[ j ] + u t 1 )
where 2 [0; 1], and V ar[ j ] is the past variance of j : In words, we assume that the …nancial sector will react to increasing variability of pro…ts, or to deteriorating macroeconomic conditions, by tightening the ‡ow of credit. Larger values of the parameter will capture a more accommodating credit market, while credit constraints will be more important at low levels of : At the steady state, with no unemployment and constant pro…ts, money demand F d j will be accommodated. The credit market is the …rst to open. This modeling trick allows to implicitly introduce a …nancial constraint. If …rms are unable to access to the needed external funds, then they won't be able to carry on their planned investment. The parameter ; that we leave exogenous, is the crucial variable to help understand the e¤ect of credit rationing on the path followed by the economy.

The Labour Market

If F s t < F d t ; then …rms will not be able to hire as many workers as they desire. Total labour demand is then equal to

Ld t = F s t + (S t 1 + H f t 1 t 1 ) w t
(hats denote constrained quantities). In the simulations below we will assume that …rms …rst reduce investment, i.e. labour demand for the construction phase. If funds are still not enough, then current production has to be curtailed as well.

The second market to open is the labour market. If L > Ld t we have unemployment, otherwise a human resource constraint will occur. E¤ective employment will thus be determined by the short side of the market

L > Ld t ) L t = Ld t L < Ld t ) L t = L
Rationing will a¤ect all …rms in the two sectors proportionally, i.e. Lj;t = L d j;t L Ld t : 1

1 Notice that an issue of strategic behaviour could arise here: knowing the rationing rule, …rms could modify their behaviour in order to obtain, once rationed, their optimal quantity. We overlook this issue, as it presupposes perfect knowledge by the …rm of the behaviour of its competitors in their own as well as in the other sector.

Production and the Goods Market

Once the labour market is closed, wages are paid, and production is carried on. The last market to open is the goods market. Supply depends on what happened previously in the sequence:

x s j;t = min[ j l j;t 1 ; j l j;t ] + o j;t 1

p a;t = w t 1 A a p b;t = w t 1 A b
Notice that l j;t embeds all the constraints that may have arisen along the sequence. On the demand side, actual employment determines the resources, and total demand

R t = L t w t + t 1 + H h t 1 X d a;t = R t + W a;t X d b;t = (1 )R t + W b;t
The short side rule applies to the goods market as well, so that we have

X d j;t > X s j;t ) H h j;t = p j;t X d j;t X s j;t X s j;t > X d j;t ) O j;t = X s j;t X d j;t
The equation for H h implicitly assumes that external demand W j is sat-is…ed in priority. The period ends at this point. The state variables that link it to the other periods are the stocks H and O; the wage level w; and the capacity (the quantity of labour stocked to carry on production in the following period.

The next section will investigate, by means of simulations, how the transition for an economy takes place after a shock. In particular, we will focus on the role of credit in facilitating the transition between di¤erent equilibria.

Out-of-equilibrium Paths

The technology parameter values we chose show a basic sector in which very few workers are needed in the construction phase, while a substantial amount of labour concurs to the production phase. On the contrary, the advanced sector is capital intensive, in the sense that most of the labour has to be applied in the construction phase. We further chose the technology parameters in such a way that overall steady state productivity (X j =L j ; j = a; b) is larger in the advanced sector2 . We investigated the path followed by the economy following a negative shock at time t = 10 in the basic sector (speci…cally, W b;10 = 0:8W b;9 ). The new steady state will then be characterized by lower wages and pro…ts, and an increase of the number of …rms in the advanced sector.

We consider the three institutional variables that a¤ect the transition towards the new equilibrium, notably the degree of wage stickiness !; the speed of …rm migration from less pro…table to more pro…table sectors , and the degree of accommodation of the …nancial sector, :

We …rst began with a low rate of …rm migration ( = 0:05), and we simulated three series of scenarios that correspond to di¤erent and alternative degree of reaction of wages to labour market disequilibria: …xed (! = 0), sticky (! = 0:05) and ‡exible wages (! = 0:5). With …xed wages (…gures 1 and 2) the economy will converge towards a sort of Keynesian equilibrium characterized by a constant rate of unemployment. Because wages do not fall, unemployment is not reabsorbed. This has an e¤ect on aggregate demand, and supply in both sectors decreases. What is interesting is that whether the …nancial sector accommodates investment or not does not make a di¤erence, as we can observe by comparing …gure 1 with …gure 2.

If we introduce a moderate reactivity of wages (! = 0:05; …gures 3 and 4), the system converges towards equilibrium. After the initial drop in pro…ts and production, due to the negative shock on employment, the decrease in wages allows unemployment to be reabsorbed, while aggregate demand increases again. This gives the …rms the resources they need to carry on production and investment, and to converge to the new steady state. Not surprisingly then, even in this case there are no major di¤erences related to the intensity of the credit constraint. In fact, the transition is …nanced out of internal funds.

The existence of a credit constraint becomes crucial when wages are very sensitive to labour market disequilibria. Figures 5 and6 show the dynamics corresponding to ! = 0:5: In this case, and with a tight credit constraint, the sharp reduction in wages following the initial unemployment a¤ects aggregate demand. Even as unemployment initially drops, the wage fund is reduced, and …rms face decreasing demand and pro…ts. As a consequence investment will be constrained, and the resulting evolution of the system is not viable (…gure 5). If …nancial markets accommodate the investment needs of …rms, as in …gure 6, then the lack of internal resources can be compensated by external money, and the economy converges towards a new steady state with full employment.

If …rms change sector more easily (i.e., with = 0:1), the tendency of the system to instability naturally increases. In fact, as …rm migration means investment e¤ort without a corresponding output (productive capacity has to be built beforehand), if too many …rms migrate at the same time, the disruption in productive capacity will feed back in lower employment, demand and again in production, in a vicious circle. Then, when wages are …xed (see …gure 7 where = 0. The equivalent with = 1 is similar and available upon request) the fall in aggregate demand will be limited, and the system will be able to recover coordination (albeit in a pseudo equilibrium with persistent unemployment)3 . But as soon as we introduce wage variability, even moderate (…gure 8), the migration of …rms will disrupt the productive capacity of the economy, and the fall of wages will a¤ect aggregate demand, revenues and the …nancing capacities of …rms. As a consequence, only an accommodating …nancial sector will allow investment to be …nanced, and the new equilibrium to be reached (…gure 9). This set of results shows that the natural tendency of the system to converge to the new equilibrium may be hampered by excessive variations in wages and or by too fast migration between sectors; these may trigger, via aggregate demand e¤ects, an important drop in the investment capacity of …rms; In turn, if this lack of resources is not compensated by the …nancial sector, the insu¢ cient investment disrupts the productive capacity of the economy, and triggers a cumulative explosive process. Therefore, re-establishing the coordination between investment and consumption and reabsorbing unemployment requires an accommodating credit policy.

We also simulated the case of a positive shock on the demand for basic goods, a shock that typically hits developing countries. In this case, the responsiveness of wages to labour market disequilibria does not seem to play a major role whereas the viability of the transition will systematically require easy access to credit. Figures 10 and 11 prove this point for rigid wages (! = 0: The other …gures are available upon request).

Robustness

The time series results reported above need to be generalized to make sure that the results do not depend on the particular set of parameters used for the simulations. To this end we thoroughly investigated the relevant parameter space to assess whether our results are robust or not.

We randomly drew (500 times) the three parameters 2 [0; 0:2] ! 2 [0; 0:5] and 2 [0; 1] to lie between the extreme values of the simulations above; for each of these draws we ran the dynamic system for 100 periods, always perturbing it with a negative external demand shock ( W b = 0:2). We then recorded, along with the parameter values, the …nal level of unemployment and other variables of interest (variance of pro…ts along the run, etc). The result of this Monte Carlo experiment strongly con…rms the conclusions we drew from the analysis of time series. Figure 12 shows a plot of unemployment for the complete sample (500 draws). It shows that many runs are not viable, as they are clustered at a near 100% level. The linear trend lines show that the non viable processes are more frequent for high levels of ! and ; thus con…rming that excessive ‡exibility has a destabilizing e¤ect on the transition process. (we also reported 'total ‡exibility', proxied by the sum +!). As for the e¤ects of …nancial constraints, the Monte Carlo experiment shows that higher levels of -a more accommodating …nancial sector-are associated with lower unemployment, thus also con…rming the …ndings of out time series analysis.

We made this impressionist statement more rigorous by building a binary regression model on the dataset created by the experiment, i.e. associating a 1 to each viable process (de…ned as a process that has a long run unemployment rate of less than 30%) and a 0 otherwise. According to this de…nition, around 25% of the processes (127 out of 500) were viable. The results of the probit regression are reported in table 1, that once again con…rms our …ndings. While it is well known that the coe¢ cients do not represent the marginal e¤ect of the regressors, their sign gives the direction of change. Thus, a positive coe¢ cient for means that more accommodating …nancial markets make the viability of processes more probable, while the negative coe¢ cients of ! and imply that excessive ‡exibility in the labour market or in the migration of …rms reduce the probability. By looking at …gure 13 we can …nally notice that the pattern is clearer for ! than for : the distribution of wage ‡exibility parameters for viable processes is clearly skewed, while for …rm migration the pattern is less clear.

While the negative role of ‡exibility in what concerns the viability of transition emerges robustly from our analysis, excessive rigidity may also be a problem. Figure 14 shows the same plots as …gure 12, for the subsample of 127 viable processes. As can be seen, to larger ! now correspond lower unemployment, while is still positively associated with unemployment. The latter e¤ect being smaller, increasing total ‡exibility within the subset of viable processes, reduces unemployment. The subset of viable processes also Dependant Variable: V iable = 1 Variable Coef f: higlights an interesting property of …nancial constraints, that show a binary behaviour: either they guarantee viability (in combination with other parameters), or they don't. And once viability is assured, there is no e¤ect of on the performance of the economy. A regression analysis on unemployment within the subset of viable processes con…rms our …ndings. Table 2 shows that is not signi…cant in explaining unemployment, and that ! and interact in a nonlinear way. If we plot the coe¢ cients for ! and of table 2, assuming in each case that the other variable takes its median value, we obtain …gure 15. The …gure shows that for very low values of ! unemployment is large, while for values larger than around 0.1 it ‡uctuates around zero. On the contrary, increasing the speed of migration of …rms has a negative e¤ect on unemployment even within the sample of viable processes.

To sum up, the disequilibrium transitions that we analyzed may apply to both advanced and emerging economies; the former are hit by increasing imports of basic goods, and the latter take advantage of low production costs and export increasing quantities of basic goods. Our simulations show that appropriate behaviours and policies should keep access to credit easy, in order to sustain the investment capacity of …rms and to help to prevent excessive disturbances in the structure of productive capacity that hamper the growth process. We further show that excessive ‡exibility in wage adjustment and in the speed of migration between sectors have a negative e¤ect on viability. Nevertheless, once the particular combination of these three factors guarantees the overall success of disequilibrium transitions, we observe that excessive wage rigidity prevents the adjustment and hence delivers excessive unemployment, and that …nancial constraints do not play a major role in explaining unemployment. We concluded that the role of …nancial constraints is binary (on/o¤): either they make the process viable, or they don't. But once the process is viable, the performance of the economy is independent from availability of …nancial means.

Concluding Remarks

Changes in the geographical distribution of economic activities, which are in the nature of the growth process, may go hand-to-hand with internal distortions that emerge from an inevitable and powerful structural change and cannot be eliminated by simply liberalizing trade and allowing the economy to be as near as possible to a state of perfect competition. While public policies that would only focus on costs conditions and hence on competitiveness of territories could amplify these distortions, which are mistakenly attributed to international trade, gradual adjustments in an environment characterized by incomplete information and irreversibility (here de…ned as the existence of a time to build) should allow the hurt country re-establishing full employment and capturing productivity gains associated with specialization.

The di¤erent paths generated by the model, corresponding to di¤erent value of key parameters, con…rm that the main issue lies not in the dramatic changes in the imports and exports ‡ows, that simply reveal changes in comparative advantages; rather, the problem lies in the way that internal (and unavoidable) distortions are dealt with. Loose monetary and exchange rate policies appear as the means required for reducing these distortions. But, the architecture of the …nancial system must also be considered insofar it is essential for determining transmission mechanisms. As a matter of fact, credit availability depends on the banks'(and shareholders') behaviour, which will be di¤erent according to the sectors'con…guration, and which is a¤ected by monetary policy in a complex way. Our purpose, here, is not to explore these transmission mechanisms, but simply to underline their extreme importance for the evolution of economies that may su¤er or take advantage of markets' openness at the world level.

Figure 1 :

 1 Figure 1: Negative shock to the basic sector. Fixed wages, low …rm migration rates, binding credit constraints

Figure 2 :

 2 Figure 2: Negative shock to the basic sector. Fixed wages, low …rm migration rates, Non binding credit constraints

Figure 3 :

 3 Figure 3: Negative shock to the basic sector. Sticky wages, low …rm migration rates, binding credit constraints

Figure 4 :

 4 Figure 4: Negative shock to the basic sector. Sticky wages, low …rm migration rates, Non binding credit constraints

Figure 5 :

 5 Figure 5: Negative shock to the basic sector. Flexible wages, low …rm migration rates, binding credit constraints

Figure 6 :

 6 Figure 6: Negative shock to the basic sector. Flexible wages, low …rm migration rates, Non binding credit constraints

Figure 7 :

 7 Figure 7: Negative shock to the basic sector. Fixed wages, High …rm migration rates, binding credit constraints

Figure 9 :

 9 Figure 9: Negative shock to the basic sector. Sticky wages, high …rm migration rates, Non binding credit constraints

Figure 10 :

 10 Figure 10: Positive shock to the basic sector. Fixed wages, low …rm migration rates, binding credit constraints

Figure 11 :

 11 Figure 11: Positive shock to the basic sector. Fixed wages, low …rm migration rates, Non binding credit constraints

Figure 13 :Figure 14 :

 1314 Figure 13: Montecarlo experiment distribution of wage and migration parameters for total sample and viable processes. Cumulate probabilities are also reported

Table 1 :

 1 Probit regression. Dep. var. is 1 if long run unemployment rate is lower than 30%, 0 otherwise. Robust standard errors in parentheses. p-values are also reported.

Table 2 :

 2 Regression results. Dependent variable is …nal unemployment. Tstats in parentheses.

	Dependant Variable: unemp
	Variable Coe¤. Variable	Coe¤.	Variable	Coe¤.
	C	3:57 (3:07)		142:9 (2:65)	!	571:9 ( 2:86)
	!	173:2	2	1515:29	(! ) 3	330211
		( 10:2)		( 2:68)		( 3:00)
	! 2	1968:1 (6:96)	4	48855 (2:61)	(! ) 6	7:98E08 ( 2:66)
	! 3	6739:9 ( 5:75)	7	4768016 ( 2:32)	! 2 3	251560 (3:07)
	! 5	33305 (4:85)		1:62 ( 0:87)
	! 6	38087 ( 4:62)	2	1:536 (0:825)
	R 2 = 0:678 Nobs.: 127

Speci…cally, we have b = 1:6; a = 0:8; b = 0:2; a = 10: Overall productivity in the two sectors is then X b =L b = 0:17 and X a =L a = 0:74

This simulation extends to a disequilibrium framework Keynes' argument for wage rigidity as a means to avoid cumulative aggregate demand -aggregate supply downward spiraling (see the chapter on wages of[START_REF] Keynes | The General Theory of Employment, Interest and Money[END_REF]. For a detailed discussion of this argument refer to[START_REF] Amendola | Wage Flexibility and Unemployment: The Keynesian Perspective Revisited[END_REF] and[START_REF] Saraceno | Wage regimes, Accumulation, and Finance Constraints: Keynesian Unemployment Revisited[END_REF]

 2. Unemployment as a function of ! assuming that equals its median value = 0:08 (black dashed line); unemployment as a function of assuming that ! equals its median value ! = 0:12 (black dashed line).