Sanggyu Shin
email: shin@aiit.ac.jp

Yoichi Seto
email: seto.yoichi@aiit.ac.jp

Mayumi Sasaki

Kei Sakamoto

Analysis of Specific Personal Information Protection Assessment in the Social Security and Tax Number System of Local Governments in Japan

Keywords: Risk Assessment, Privacy Impact Assessment, Privacy risk, Social Security and Tax Number System, Specific Personal Information Protection Assessment

A law in Japan has been established concerning the My number system or the use of numbers for identifying specific individuals in administrative procedures in local governments. The law requires local governments to implement the specific personal implementation protection assessment for social security and tax number systems. In this paper, we analyzed the assessment reports of the specific personal information protection assessments conducted by local governments. We did the analysis in two directions: (1) adequacy of risk assessment and measures, and (2) reuse of the assessment report. Our analysis shows that there was a description of assessment on the risk assessment items, but there were many assessment reports with missing assessment on some operations.

Introduction

On May 24, 2013, the Act on the Use of Numbers to Identify a Specific Individual in the Administrative Procedure, also known as the My Number law, was raised. From this law, the Social Security and Tax Number System or the My Number system came in. The My Number system is used to confirm that information on individuals possessed by multiple agencies such as administrative agencies and local governments are information of the same person. This system advocates a fairer and more just society, enhanced public convenience and improved administrative efficiency [START_REF]Act on the Use of Numbers to Identify a Specific Individual in Administrative Procedures[END_REF].

From October 2015, the government has enforced the My Number law, and notified the residents of their My Number numbers. The personal information including My Number is called Specific Personal Information.

Protection Assessment is done to prevent infringement of privacy of personal information and ensure the trust and protect the rights of citizens and residents [START_REF]Description of the specific personal information protection evaluation guidelines[END_REF]. Af-ter protection assessment, each local government unit must conduct their risk assessment as assessment report [START_REF] Takashi | Improper specific personal information protection evaluation shakes "My number" system[END_REF].

In this paper, we analyzed the report published by the local governments in the following perspectives:

1. Adequacy of risk items, and 2. Re-use of the Assessment report.

In other countries, privacy impact assessment (from now on referred to as PIA) has been carried out to preliminarily assess the influence on privacy when introducing or repairing a system involving the acquisition of personal information, and taking measures to avoid or mitigate privacy risk [START_REF] Yoichi | Practical Privacy Risk Assessment Technique[END_REF].

In the PIA, there are two studies on the validity of impact assessment: one is the assessment of the suitability of the PIA applied to the biometrics system. The other is a study evaluating the effectiveness of the PIA itself.

Officials in charge of the administrative organization self-evaluate the Specific Personal Information Protection Assessment about the system and operation. On the other hand, the PIA does not include the operation, but only the system is assessed by a specialized neutral third party. The government has published protection assessment as equivalent to PIA, but as stated above, PIA and protection assessment are fundamentally different.

This paper analyzes and assesses whether the Specific Personal Information Protection Assessment prescribed by the My Number law is properly implemented by local governments based on the assessment report issued by the local governments.

Related Works

There are two similar researches on the appropriateness of risk assessment in conjunction with PIA. Protection assessment concerning specific personal information was implemented in 2015, and no case study on the protection assessment was found. The protection assessment is conducted only in Japan, while the PIA is an assessment method that has international standards and is implemented in other countries. In the PIA, there are two cases of research on the appropriateness. First, Kush Wadhwa et al. applied PIA to biometric systems then assessed the appropriateness of the procedures for PIA by ranking [START_REF] Wadhwa | SAPIENT project supporting fundamental rights, privacy and ethics in smart surveillance technologies[END_REF]. They assumed that the PIA method is useful and evaluated its adequacy as to whether the implementation procedure is appropriate for the case of PIA. For example, their work assessed whether the report release procedure is appropriate or not. The other related work is a case study where Sakamoto et al. conducted the effectiveness assessment of PIA itself [START_REF] Sakamoto | Assessment of effectiveness of personal information impact assessment[END_REF]. They assessed the effect of how much privacy risk could be reduced by implementing PIA using the risk assessment method developed based on the international standard ISO 22307. In other words, the effectiveness of PIA is quantitatively assessed from two viewpoints: visualization of privacy risk on personal information and improvement of awareness of stakeholders concerning personal information protection.

The protection assessment to be implemented in Japan is stipulated by the guidelines so that risk assessment is carried out in a mixture of system and operation by self-evaluation of officials in charge of the administrative organizations who have used the system [START_REF] Yoichi | Practical Privacy Risk Assessment Technique[END_REF] [START_REF] Supervised | Specific personal information protection practice guidelines for local governments[END_REF]. Due to these reasons, the two assessment methods are completely different, and it's hard to apply the assessment method implemented in the PIA to the Specific Personal Information Protection Assessment.

In our work, we evaluate whether the assessment is done properly by analyzing the assessment report which is the result of the protection assessment of the specific personal information.

3

Specific Personal Information Protection Assessment

Outline of Specific Personal Information Protection Assessment

In the case of the My Number system, it was imperative to implement the protective assessment as one of the protective measures against the task of handling specific personal information [START_REF]Act on the Use of Numbers to Identify a Specific Individual in Administrative Procedures[END_REF]. Fig. 1 shows an overview of protective assessment.

Fig. 1. Overview of Specific Personal Information Protection Assessment

Protection assessment for specific personal information aims to prevent the leakage of specific personal information and other accidents beforehand by ensuring proper handling of specific personal information files such as the My Number number, to prevent and protect rights and interests of residents. That is the basic idea of the protection assessment. Its purpose lies in the following.

1. Preventing infringement of rights and interests such as personal privacy by prior response, and 2. Ensuring the confidence of citizens and residents through appropriate disclosure of information.

3.2

Procedure of the Specific Personal Information Protection Assessment

In the protection assessment, it is obligatory to carry out either essential item assessment, priority item assessment, or all item assessment by threshold judgment. Indicators of threshold judgments include the number of people to be handled, the number of persons dealing with specific personal information files (from now on referred to as the number of handlers), and the occurrence or not of a serious accident concerning specific personal information at the assessment executing agency.

For example, if the target number of people is 300,000 or more, all items are assessed. For more than 100,000 or more are less than 300,000 people, priority item assessment is required. For less than 100,000 people, only the essential item assessment is obliged.

If the number of handlers is 500 or more or a serious accident related to protection of specific personal information has occurred within the past year, it switches from priority item assessment to all item assessment, and essential item assessment to priority item assessment. However, if the target number of people is less than 1,000, implementation of protection assessment is not obligatory.

After the all item assessment report is prepared by the local government, it is necessary to publicize the assessment report, request the opinion of the residents, and do an appropriate review of the assessment report after fully considering the obtained opinion. After consideration of the assessment report, they are submitted to the Personal Information Protection Committee after undergoing a third party inspection. Table 1 shows an example of the assessment items of all item assessment report [START_REF]Specific personal information protection evaluation guidelines[END_REF].

Table 1. Examples of assessment items of all item assessment report III Risk measures in the handling process of specific personal information file 1. Name of specific personal information file ① 2. Acquisition of specific personal information (excluding acquisition through information provision network system) Risk 1: Risk of obtaining non-purpose acquisition The content of measures to prevent the acquisition of information other than the target peoples ②

The content of measures to prevent obtaining non-necessary information ③

Contents of other measures ④

Is the measure of risk sufficient?

[ ⑤ ] <Option> 1) Putting particular emphasis 2) Enough 3) Issues remain Hereinafter omitted

Hereinafter omitted

The method of describing the assessment report includes the method of writing an outline in the blanks shown in ① to ④ in Table 1 and the selection description method shown in ⑤. For example, in ②, actions that correspond systematically such as "restrict accessible terminals" and measure concerning operation (human / organizational) such as "to verify identification based on notification/application details or identification documents" are described. In other words, it is necessary to assess both system and operation for every item and describe each measure without omissions. In the selection description, chooses one from options such as 1) Putting particular emphasis, 2) Enough, and 3) Issues remain, etc. In the case of PIA, risk assessment targets are not administrative (operations) but systems. The privacy commissioner issued the standard guideline and risk assessment carries out the assessment based on this guidance. Also, risk assessment is not classified by the number of personal information handled [START_REF] Yoichi | Practical Privacy Risk Assessment Technique[END_REF].

Issues of specific personal information protection assessment

Although protection evaluation is said to be equivalent to PIA adopted in other countries, there are the following differences when compared with PIA.

1. The assessment object is "clerical work handling specific personal information file," the definition of administrative tasks is unclear, and the system and operation related to the target functions (organizational and human) are mixed. 2. While PIA is evaluated by a third-party organization with neutrality and expertise, protection evaluation is a self-assessment by the system operator (officials such as administrative agencies) and self-declaration by the chief, etc. 3. Risk assessment manual etc. for protection evaluation still has not been sorted out.

Therefore, administrative agencies are preparing assessment reports by individual risk analysis methods.

As described above, there is a possibility that the risk assessment is not properly implemented in the protection assessment on specific personal information. Therefore, using all the item assessment reports released by the local governments, we analyze whether the risk assessment is properly implemented from the two following viewpoints.

1. Adequacy of risk assessment and measures: assess the excess and deficiency of assessment standard and safety control measures created separately for system and operation. 2. Reuse of the assessment report: We analyze the assessment report published by the local governments and assess the situation on reuse.

4

Analysis of all item assessment report 4.1 Analysis method

As described in Section 3.3, protection assessment and PIA have different targets and procedures. For this reason, we analyzed whether protection assessment deals with the protection of specific personal information in the My Number system based on the two following points.

Adequacy of risk assessment and measures.

In the protection assessment, for example, each local government implements measures of risk countermeasure against the risk items described in the all item assessment report. However, there is a possibility that risk assessment and safety control measures will not be considered sufficiently in the protection evaluation. From this issue, three issues 1 to 3 are conceivable.

1. For risk countermeasures, since risks (threats and vulnerabilities) are different in the system and operation, they should be evaluated and described separately, but many local governments expressed mixed opinions about systems and operational risk mitigation measures. 2. The basis for the content of the description for the risk item is unclear. Although the risk item shown in Table 1 is presented from the central government, there is no explanation about its basis. 3. Risk items in the assessment reports are uniform entries and the specific level when the local governments consider the risk countermeasure is not indicated. For that reason, it is conceivable that local governments differ in the way of grasping risks and the level of description. There are issues such as whether adequacy judgment is carried out is subjective, such as "adequate measures" for risks in situations where countermeasure standards are not presented. As a result, the local governments that assess can select "Enough" etc. depending on their personal opinions.

Reuse of assessment reports.

Reuse of the assessment report has two viewpoints. One is to reuse assessment reports of other local governments that precede the same affairs, or samples provided by the central government. The second one is to reuse the content of the assessment report of the administrative office that was previously assessed in the same local government in the assessment of another office work.

Selection of analysis targets

As described in Section 3.2, the protection assessment is classified into three assessments based on threshold judgment, essential item assessment, priority item assessment, and all item assessment.

In this paper, we focused the assessment report of all items. Many officials deal with a lot of specific personal information in the all items assessment. Therefore, the risk of leakage of specific personal information and other accidents is high thus more detailed and accurate risk measures are required.

As of June 2015, 221 assessment reports of all items have been released by the Personal Information Protection Committee. We investigated 10 cases of all item assessment reports.

Selection criteria for the all item assessment report to be investigated are as follows.

1. Official assessment report released by the Personal Information Protection Committee. 2. Assessment report for the same affairs, that is, "affairs concerning the basic resident register." 3. Selection from local governments in various parts of Japan that do not depend on locality: 9 assessment reports corresponding to approximately 10% of all item assessment documents (80 cases). 4. Select the description procedure that is presented from the central government as a criterion to compare with all the item assessment reports of the local government.

Table 2 shows the basic data of the local governments that were selected as assessment targets [START_REF]From demographics by each local government[END_REF]. In the protection assessment, there is no procedural manual on risk assessment, so the assessment is left to the administrative agencies and local governments. Also, the skill level of the person in charge who performs the assessment is not stipulated. In this section, we analyze whether each local government described appropriate risk response for risk assessment. The evaluation criteria were prepared according to the safety measure standards shown in the (Separate) Safety Management Measures for Specific Personal Information (Operator's Guide). We prepared assessment criteria by classifying risk correspondence to be implemented for each risk item into systematic correspondence and human organizational correspondence [START_REF]Personal Information Protection Commission, Guidelines on proper handling of specific personal information[END_REF].

We analyzed to compare each risk items which are assessment criteria classified into system-related measures and measures concerning the operation of the "III Risk measures in the handling process of specific personal information" about the basic resident register file with all item assessment reports to be analyzed which published by local governments. Fig. 2 show the example of the comparative assessment.

Fig. 2. Comparison of all item assessment report and assessment standard

The result of the comparison is indexed in Table 3 to confirm the excess or deficiency for each corresponding risk item. We roughly distinguished that the assessment index of risk to three stages (Table 3) because it is hard to fix the index based on a logical basis. This assessment index was decided based on a discussion with the expert on PIA.

Table 4 shows the distribution and the assessment value of the assessment index concerning the risk correspondence on the system in each local government. The assessment value is calculated by adding the value of multiplying risk number by the assessment index and dividing by the number obtained by subtracting the number of items not subject to evaluation from the total number of items (49).

Table 3. The category of assessment of the risk response.

Assessment results

Assessment index

The risk correspondence indicated by the evaluation standard is being satisfied. Furthermore, the risk described corresponding to the evaluation criteria is supported.

3

The only parts of the risk management that are shown in the assessment criteria are described. 2

The risk correspondence indicated by the assessment standard isn't mentioned. For example, in the case of City A, it is calculated as follows.

Assessment value = (3×7+2×12+1×5) ÷ (49-25) = 2.08

The assessment index when not mentioning the risk correspondence indicated by the assessment standard at all is 1 point. Also, since the assessment index when only a part of the risk correspondence is indicated in the assessment criteria is described is 2 points. When the average value of the assessment index is 2 points or less, there is a possibility that proper risk response could not be made. The fact that the average value of the assessment index is 2 points or less means that many risk items did not cope with the risk indicated by the assessment criteria.

Table 5 shows the distribution and the assessment value of the assessment index concerning the risk correspondence on the operation in each local government. As for the operation, the assessment index is lower as a whole compared to the system. This is because local governments do not mention countermeasures concerning operations. They only describe the risk correspondence concerning the system in risk countermeasures. In other words, there is a possibility that the all item assessment report announced previously was reused by simply copying and pasting. In the case of preparing the all items evaluation document by reuse, it may be considered that the examination of risk assessment is inappropriate and it is possible that the existing reason of the system itself will be gone. We analyzed the identity confirmation information file of all items assessment report selected in section 4.2. We compared the corresponding items in the description procedure and its similarities concerning the "III Risk measures in the handling process of specific personal information."

Specifically, we count the number of characters for which the Description of the assessment report and the statement of description are identical and then calculate the ratio. The higher the reuse rate, the higher the likelihood of reuse. Table 6 shows the reuse rate by the local governments. All item assessment report in which the reuse rate exceeded 50% is 44% (4 out of 9: A/B/C City and D District). All item assessment report in which mistook the incorrect legal number is 89% (8 out of 9: local governments excluding B City). All item assessment report in which misprinted typographical errors similarly is 67% (6 out of 9: A/B/C/G City and D/I District).

For reasons that the reuse rate for each local government exceeds 50%, there may be uniformity in the description format of all item assessment reports. Thus, the description contents are similar. Therefore, it can't be said that there is a problem in reuse and it can be said that it is effective means to reuse to improve efficiency. However, it is important that proper risk assessment and countermeasures are implemented, and confirming this is the responsibility of third party inspection. If the inspection committee (or the personal information council) functions properly, it can be confirmed whether or not there is a problem with reuse.

Conclusion

In this paper, we analyzed from the viewpoint of all items assessment report the specific personal information protection assessment system for all item assessment. As a result of the analysis, the following problems were found out.

1. Since risk assessment guidelines do not exist, cases were found where appropriate risk assessment was not conducted for each local government. 2. Because the legal status of third-party inspection is unclear, there are local governments whose third-party inspections are not functioning effectively.

To deal with these problems, it is necessary to consider countermeasures from both the improvement in the current system and the review of the institutional design. Improvement measures in the current system are to prepare guidelines for common evaluation of local governments [START_REF]Related manual of Specific Personal Information Protection Assessment[END_REF]. By conducting assessment and inspection according to the guidelines, we believe that appropriate correspondence without missing will be possible, and variations in responses among local governments will be improved. Also, the load on the evaluator can be reduced.

Table 2 .

 2 Basic data of local governments

	Unit (people)

Table 4 .

 4 The situation of corresponding to the risk (System).

	1

Table 5 .

 5 The situation of corresponding to the risk (Operation).Many descriptions of all items assessed by local governments are similar to the Procedure for Specific Personal Information Protection Evaluation Procedure (draft) on affairs related to basic residential ledger (from now on referred to as the Procedure) exemplified by the Ministry of Internal Affairs and Communications[START_REF]Personal Information Protection Commission, My number protection assessment Web[END_REF][12].

		All 49 items	3	Operation 2 1	0	Assessment index (Average of all item)
		A city	11	17	7	14	2.11
		B city	12	21	2	14	2.29
		C city	9	16	11	13	1.94
		D district	12	12	12	13	2.00
		E city	8	17	11	13	1.92
		F city	12	14	10	13	2.06
		G city	8	16	12	13	1.89
		H city	11	13	12	13	1.97
		I district	36	0	0	13	3.00
	5.2	Reuse of assessment reports

Table 6 .

 6 Local government reuse rate.

		A city	B city	C city	D district	E city	F city	G city	H city	I district	Average
	Reuse rate	52.1 64.4 38.5	75.9	44.0 47.2 55.6 43.5	32.7	50.5

Acknowledgments. This research carried out in the Project Based Learning in the Advanced Institute of Industrial Technology. In advancing the PBL, we got the cooperation of Kazuhiro Midorikawa, Yuta Kurosawa, Okimura Seiji, and Xiaofei Ma. We would like to express our appreciation here.


Olfa Chebbi

Ezzeddine Fatnassi

The multi depot one-to-one pickup and delivery problem with distance constraints: Real world application and Heuristic solution approach

Keywords: Vehicle routing problem, Multi-depot, pickup and delivery requests, transportation problems

This paper presents the development of the multi depot oneto-one pickup and delivery problem with distance constraints problem. This problem involve routing vehicles in a multi depot network topology to satisfy a set of pickup and delivery requests subject to a maximum allowable distance constraint. A problem denition is given and a real world application is proposed for that problem. An approximate solution approach which divides the problem into several subproblems and solve them to optimality is also proposed. Computational experiments show that the proposed solution approach reach good quality solutions is a reasonable computational time.

Introduction

Real-life urban on-demand passenger's transportation problems represent a high complex type of problems. In fact, these problems involve a variety of hard constraints which must not been violated. Such constraints involve multi-dimensional vehicle capacity, route duration restriction, time windows, exclusive travels and so on. These problems involve also several complex objective functions which are more complex than the classical distance minimization as several real life factors must be taken into account. However and despite the important interest of these problems, they have received little attention in the literature from an academic point of view.

Generally, real-life urban on-demand passenger's transportation problems are related to the theoretical vehicle routing problems. The vehicle routing problem (VRP) was rst proposed by Dantzig and Ramser in 1959 [START_REF] Dantzig | The truck dispatching problem[END_REF]. VRP involves a set of key decisions in order to nd a least costs set of customers' sequences to be visited by each vehicle. VRP involves generally several constraints such as distance, capacity, time and cost constraints.

In the literature, several variants of VRP have been studied which meet and address condition of several real world applications of VRP. One could note for example the capacitated VRP(CVRP) [START_REF] Prins | A simple and eective evolutionary algorithm for the vehicle routing problem[END_REF], the heterogeneous VRP(HVRP) [START_REF] Coelho | An ilsbased algorithm to solve a large-scale real heterogeneous eet vrp with multi-trips and docking constraints[END_REF], VRP with time windows , VRP with pickup and delivery (PDP) [START_REF] Zhu | A multi-objective memetic algorithm based on locality-sensitive hashing for one-to-many-to-one dynamic pickup-and-delivery problem[END_REF], the multi depot VRP (MDVRP) [START_REF] Lalla-Ruiz | An improved formulation for the multi-depot open vehicle routing problem[END_REF] and so on. For a more clear survey on VRP and its extension, the reader is refereed to [START_REF] Berbeglia | Dynamic pickup and delivery problems[END_REF].

The PDP is the problem where the service required by a customer needs both pickup and delivery service. The PDP can be further subdivided to the many to many PDP, the one to many to one PDP and the one to one PDP. For a more classication of PDP the reader is referred to the survey paper of Berbeglia et al. [START_REF] Berbeglia | Dynamic pickup and delivery problems[END_REF].

The VRP and its several variants such as the PDP and the MDVRP could include several constraints and are known to be NP-Hard problems [START_REF] Berbeglia | Dynamic pickup and delivery problems[END_REF]. The relative complexity of these problem results on a long computational time to nd optimal solution especially for large size problems. Consequently, heuristics and metaheuristics approaches have been widely applied and developed to solve large VRP problems. In fact, approximate methods have been able to provide good quality solutions within reasonable computational time.

Based on the works from the literature, relatively new variants of VRP could be proposed to tackle real world application of routing problems. For instance, we could note the works of Sombuntham and Kachitvichyanukul [START_REF] Kachitvichyanukul | Two solution representations for solving multi-depot vehicle routing problem with multiple pickup and delivery requests via pso[END_REF] where they proposed a particle swarm optimization algorithm for multi-depot vehicle routing problem with multiple pickup and delivery requests or the multi-depot pickup and delivery problem with a single hub and heterogeneous vehicles [START_REF] Irnich | A multi-depot pickup and delivery problem with a single hub and heterogeneous vehicles[END_REF]. These works proves that the joint study of multiple depot and pickup and delivery problems is an interesting eld to develop. However, one could note that none of the recent works in the literature of the multi-depot pickup and delivery problems proposed to add distance constraints related to VRP. Also, one could note that to the best of our knowledge the multi-depot variant of the one-to-one PDP has not been studied in literature before [START_REF] Lahyani | Rich vehicle routing problems: From a taxonomy to a denition[END_REF] [START_REF] Berbeglia | Dynamic pickup and delivery problems[END_REF].

Consequently in this paper, we extends the works in the literature by focusing on the multi-depot one-to-one PDP with distance constraints problem. Starting from an urban on-demand passengers transportation problem related to automated transit system, we motivate the multi depot one-to-one PDP with distance constraints problem. We propose also an adapted linear programming heuristic in order to solve large size instances of the proposed problem in a fast computational time. Finally, the proposed solution approach is proved to be very eective by testing it on a carefully generated set of instances based on our real world context. Consequently, Section 2 presents the real world application of the multi depot one-to-one PDP with distance constraints. Section 3 develops the problem formulation. Section 4 provides a description of the resolution methodology. Section 5 describes the computational results. Finally, Section 6 concludes the paper.

In this paper, we focus on the multi depot one-to-one PDP with distance constraints by studying its real world urban on-demand passengers transportation application. In fact, there is several transportation systems that are designed to move people in urban areas. Examples of these systems include subway, bus, train, bus rapid transit (BRT), light rapid transit (LRT), automated transit network (ATN) and so on. Fig. 1: ATN' vehicles ! Among these system, one could focus on the ATN systems. ATN is designed as a public transportation tool to move passengers within urban areas. ATN offers an on-demand non-stop, origin-to-destination transportation service for its users over a dedicated network. ATN uses a set of fully automated vehicles carrying passengers from station to station. ATN'vehicles run on exclusive, gradeseparated set of guideways (see Figure 1) . ATN oers an unique transportation service. In fact, ATN'stations are o-line. This feature allows vehicles to travel from origin to destination without any intermediate stops. Furthermore, ATN transportation service is done on-demand where users could choose their time and way of travel. Therefore, ATN oers a taxi-like transportation service. ATN transportation features are quite dierent from any other automated guideway transit service (AGN) such as LRT, BRT and streetcars.

In the literature, the main features of ATN are dened as follows:

Small vehicles available for the moving an individual or small group traveling together by choice. direct origin-to-destination transportation service without any intermediate stops.

on demand transportation service. fully automated driverless electric vehicles.

! source:http://www.ultraprt.net/multiVehicle.htm A literature review published in 2005 [START_REF] Cottrell | Critical review of the personal rapid transit literature[END_REF] states that there is more than 200 research papers related to ATN. More recently, several operational and strategic optimization studies related to ATN were published such as network design [START_REF] Zheng | Network design for personal rapid transit under transitoriented development[END_REF], station design [START_REF] Won | Optimal design of personal rapid transit[END_REF], dynamic routing [START_REF] Chebbi | Modeling on-demand transit transportation system using an agent-based approach[END_REF][13], simulation [START_REF] Fatnassi | Two strategies for real time empty vehicle redistribution for the personal rapid transit system[END_REF], [START_REF] Chebbi | Proceedings of the Second International Afro-European Conference for Industrial Advancement AECIA[END_REF] energy minimization [START_REF] Mrad | Optimal consumed electric energy while sequencing vehicle trips in a personal rapid transit transportation system[END_REF], passengers waiting time [START_REF] Lees-Miller | Minimising average passenger waiting time in personal rapid transit systems[END_REF] total traveled distance [START_REF] Fatnassi | Discrete honeybee mating optimization algorithm for the routing of battery-operated automated guidance electric vehicles in personal rapid transit systems[END_REF][15], eet size [START_REF] Chebbi | Optimal eet sizing of personal rapid transit system[END_REF], optimized operational planning [START_REF] Chebbi | Reducing the wasted transportation capacity of personal rapid transit systems: An integrated model and multi-objective optimization approach[END_REF][11] and so on.

Starting from all these features, one could note that the transportation service for ATN consists on pickup passengers from a predened station in order to deliver them to another station. Consequently, the ATN has a strong relation with the PDP problem. Also as the ATN uses a set of driverless vehicles with limited battery capacity, we could found distance constraints related to the routing of ATN vehicles. Finally, as the ATN'network could have multiple depots where initially the ATN vehicles are located, routing vehicles in the ATN context has also a strong relation with the Multi-depot VRP.

However and in the literature, routing problems related to ATN considered only the single depot network topology with dierent objective such as energy minimization [START_REF] Fatnassi | Discrete honeybee mating optimization algorithm for the routing of battery-operated automated guidance electric vehicles in personal rapid transit systems[END_REF], eet size [START_REF] Chebbi | Optimal eet sizing of personal rapid transit system[END_REF], waiting time of passengers [START_REF] Lees-Miller | Minimising average passenger waiting time in personal rapid transit systems[END_REF] and so on. Consequently and based on all these features and this gap in the literature, we could state that routing driverless electric vehicles in the ATN'network has a strong relation with the multi depot one-to-one PDP with distance constraints.

In the next section, we detail the theoretical problem formulation related to the ATN.

Problem formulation

In this section, we present the formal problem description and denition of the multi depot one-to-one PDP with distance constraints.

Problem description

Generally in VRPs, a customer is described as a place that must be served by a vehicle from the depot. In this paper, the classic term of customer is replaced by a more general term of "travel". The travel reects the pickup and delivery transportation service that must be done within the one-to-one PDP. For a PDP problem, a travel is represented by a commodities or a group of persons that must be collected from an origin location and must be delivered to a destination location. As we are treating the one-to-one PDP, the transportation service is done by direct shipment from origin to destination. As each travel has dierent physical locations, each location can play only one of these three roles: pickup location, delivery location, or depot. Consequently, each location may have several passengers or groups of passengers to be picked up and delivered to several other locations. The transportation situation happening in our problem can be depicted in Figure 2.

Our problem is based on the following assumptions: Each travel contains information concerning transportation demand. In order to satisfy travel i, the central control system must assign an empty vehicle in order to satisfy a transportation service from a pickup location DS i to delivery location denoted AS i . The service should be provided at the desired departure time, DT i , and delays are not permitted. Each travel, i, has a specic arrival time AT i .

Our objective is to design a set of least-cost journeys that start and end at the depot, are capable of accommodating all travel requests within the allocated time frame and under several constraints such as distance and time window constraints.

Generally, in our problem the vehicles routes have to be constructed in such a way that:

The total energy consumption is minimized. All the travels must be fullled.

In addition, the following restrictions must be met: vehicles could serve only one travel at a time. Each travel is served by exactly one vehicle. The number of routes starting from a depot location must be equal to the number of route ending in the same depot location. The total duration of each route does not exceed a preset limit. As in our real world application we are using electric ATN'vehicles with limited electric battery capacity, the total route length must not exceed the maximum allowable travel time by the electric battery. Each request must be served exactly at its starting time.

Formal Graph Denition of our problem

∈ E = {(i, j) | i, j ∈ V }. Note that E * = {(i, j) | i, j ∈ V * }.
We add edge e to set E when one of the following conditions is satised.

for each nodes (i, j) ∈ V * , we add an edge if and only if the departure date of travel j exceeds or equals the sum of the arrival time of travel i and the time needed to move from the arrival location of travel i to the departure location of travel j. The cost of this edge is the energy used for traveling from the arrival location of travel i to the departure location of travel j and of traveling from the departure location of travel j to the arrival location of travel j. for each node i ∈ V * and each depot d ∈ D, an edge (d, i) is added with the cost of moving from d to the departure location of travel i plus the cost of moving from the departure location of travel i to the arrival location of travel i. we add a nal set of edges (i, d) for each node i ∈ V * and each depot d ∈ D. The cost of these edges includes the cost of moving from the arrival location of travel i to d.

The resolution methodology

In this section, we present our resolution methodology for the problem considered above which we call linear programming heuristic (LPH). Our LPH is based on the principles presented in Algorithm 1.

Based on Algorithm 1, we rst solve a relaxed linear program in order to nd set of roads starting and ending at one of the dierent depot in the network. The relaxed linear program founds unfeasible roads as we relaxed the distance constraints. Next our LPH and in order to nd feasible roads and therefore feasible solution would use an optimal mathematical model to get feasible roads from the set of unfeasible roads. Next, we present more details of the implemented LPH.

Algorithm 1 LPH(The network N , The set of travels T 1: Construct the graph G 2: Solve the relaxed Linear programm (see Section 4.1) 3: for (each obtained routes Ri) do 4:

if Ri is a feasible route then 5:

Add Ri to the nal solution 6: else 7:

Construct a subproblem based on the nodes present in Ri.

8:

Solve the new small problem to optimality 9:

Add the obtained new roads to the nal solution 10: end if 11: end for 12: Return the nal solution

The relaxed linear program

This section presents the relaxed linear program that the LPH will use during its search process.

We rst introduce the following integer variable:

x ij = { 1 if arc (i,j) is selected to match i to j 0 otherwise
In our heuristic, we rst solve the following relaxed linear program.

: Min

∑ (i,j)∈E c ij x ij ∑ j∈δ + (i) x ij = 1∀i ∈ V * ∑ j∈δ -(i) x ji = 1∀i ∈ V * ∑ j∈δ + (i),k∈δ + (i) x ij = ∑ x ki ∀i ∈ D x ij ∈ {0, 1}∀ (i, j) ∈ E
Objective function 4.1 minimizes the total energy consumption of the system. Constraints 4.1 and 4.1 ensure that each travel node is served exactly once. Constraints 4.1 ensure that the number of routes starting from a given depot is equal to the number of routes ending in that depot.

However solving this linear program could result on a set of infeasible tour as we do not include maximum distance constraint on it. To x this dilemma, we propose a specic approach which is presented hereafter.

Approach

Our algorithmic approach is based on the fact that unfeasible routes which violate maximum allowable constraints could be corrected using a valid mathematical formulation of the proposed problem. In fact by solving the relaxed linear program, we could obtain two types of routes: feasible routes and unfeasible routes. Based on our approach, we consider the feasible routes as part of the nal solution. The unfeasible routes would be corrected in order to make them respect the maximum allowable distance constraints. In fact from each unfeasible routes, we construct a small routing problem based on its nodes. This small problem would be solved to optimality using a valid mathematical formulation of our problem. This valid mathematical formulation is taken from the works in the literature of Almoustafa et al. [START_REF] Almoustafa | New exact method for large asymmetric distance-constrained vehicle routing problem[END_REF] while adding the multiple depot constraints to it. Based on these principles, the nal feasible solution would be constructed iteratively.

Computational experiments

We now present the computational study performed to investigate the results of our LPH for solving the proposed optimization problem. An analysis of the obtained results is also performed to prove the eciency of our algorithm.

Test Instances

The proposed algorithm is implemented using the C++ language and tested on a laptop with an Intel(R) Core (TM) i3 CPU M 380 2.53 GHz processor and 3 GB RAM (Windows 7 64-bit). Since we are treating a real world application of the GVRPMDMPDRDC related to the ATN, we based the testing instances on recent works related to ATN [START_REF] Chebbi | Reducing the wasted transportation capacity of personal rapid transit systems: An integrated model and multi-objective optimization approach[END_REF]. In fact our instance generator is based on the Corby network which represents a real case of routing ATN'vehicles in urban areas. This network represents a realistic case study developed by Bly and Teycheene [START_REF] Bly | Three nancial and socio-economic assessments of a personal rapid transit system[END_REF]. Corby is a town in Northampton, (UK) with a population of approximately 50 000. It oers a good example for testing the ATN feasibility in a relatively new town. This network has 14.2 km of ATN guideways. The Corby network has 15 stations and four depots.

Based on this network, we generated 100 instances where the number of travels varies between 10 and 100 in a steps of 10. Consequently and for each travel 'size, we generated 10 instances. The list of travels and its characteristics were based on the works from the literature of Mrad and Hidri [START_REF] Mrad | Optimal consumed electric energy while sequencing vehicle trips in a personal rapid transit transportation system[END_REF] and Mrad et al. [START_REF] Mrad | Synchronous routing for personal rapid transit pods[END_REF]. The maximum allowable time limit for each route was taken to be equal to 40 minutes [START_REF] Chebbi | Reducing the wasted transportation capacity of personal rapid transit systems: An integrated model and multi-objective optimization approach[END_REF]. We note also that all the mathematical models were solved using IBM-Cplex 12.2 " . " Details about Cplex could be found in https://www-01.ibm.com/software/commerce/optimization/cplex-optimizer/

Computational results

Results of our method are exposed in Table 1. To assert the quality of the obtained solutions we used the GAP metric. The GAP is obtained as follows: GAP = ( (SOL-LB)

LB

) × 100 We should note that LB is the linear relaxation of the presented mathematical formulation presented in the literature [START_REF] Almoustafa | New exact method for large asymmetric distance-constrained vehicle routing problem[END_REF].

Table 1 illustrates that the LPH method provides good quality solutions. In fact, the LPH founds an average GAP of 2.435% in 0.132 seconds. As shown in Table 1, using the LPH method results on obtaining remarkable low GAPs which varies from 0.635 % to 5.075 %. Moreover, the GAP with respect to the lower bound values is below 6%. These results mean that the algorithm is capable to converge to a good solution even starting from an unfeasible one which is actually a good point for our algorithm. The good performance of the LPH is further compounded by the fact that it consume small computational time (less than 0.3 seconds). This is due mainly to the straightforward principles that the LPH uses. In fact by solving at each time a relaxed linear program, it has the ability to determine good parts of the nal solution quickly. The multi depot one-to-one PDP with distance constraints problem has been introduced and formalized in this paper. This is a new VRP that arises in real urban contexts. The goal of this problem is to carry a set of pickup and delivery operations at a minimum costs subject to dierent constraints related to the time windows and total traveled distance for vehicles. A real world application related to the multi depot one-to-one PDP with distance constraints was proposed. Our application arises in the context of ATN in order to carry a set of passengers from origin to destination locations. The proposed problem was formulated and a straightforward linear programming heuristic was proposed to solve it. Computational tests have been carried out on instances with dierent number of travels while representing realistic network contexts. The results obtained from computational tests show the ecacy and the eectiveness of the proposed approach. The most innovative aspect of this approach is its ability to extract goods part of the nal solution while starting from an unfeasible solutions. Future developments in this eld could address the introduction of stochastic travel time between locations of the treatment of the proposed routing problem in a dynamic context by the tool of simulation.

Fig. 2 :

 2 Fig.2: The VRP with one to one transportation requests.

  More specically, our problem is based on a non-directed graph G = {V, E}, where V = {1, 2, ..., n, d 1 , d 2 , ..., d k } is the set of vertices in the graph. d 1 , d 2 , ..., d k represent the dierent k depots in the network. Let the vertex set V * = {1, ..., n} corresponds to the set of travels. E represents the set of edges, with e

Table 1 :

 1 The Obtained Results

	Number of Travels Average Gap % Average Time (seconds)
	10	0.635	0.037
	20	0.800	0.050
	30	1.649	0.067
	40	1.641	0.071
	50	2.655	0.099
	60	2.682	0.124
	70	3.782	0.151
	80	2.774	0.212
	90	2.655	0.234
	100	5.075	0.271
	Average	2.435	0.132
	6 Conclusions

The real world application of the multi depot one-to-one PDP with distance constraints


Mohanad Halaweh
email: mohanad.halaweh@afu.ac.ae

Intention to Adopt the Cash on Delivery (COD) Payment Model for e-Commerce Transactions: An Empirical Study

Keywords: E-commerce, Online Payment Methods, Cash on Delivery (COD), Adoption

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Since the appearance of the first e-commerce website in 1995, various methods of online payment for e-commerce purchases have been used, including credit cards, debit cards, smart cards, e-cash, e-checks, e-wallet, and micropayment. However, during the past few years, a new method of payment called cash on delivery (COD) has been increasingly used. COD is different from all other methods of payment in terms of its processing, the time and place that the payment is made, the parties involved, and many other issues, including its security and privacy assurance (Reference removed). COD enables customers to make a payment in cash at the time a product is delivered to any location the customers choose. The use of this method is increasing in some countries. For example, in Vietnam, COD is accepted by 24 out of the 33 (73%) surveyed e-commerce companies [START_REF]E-and m-commerce and payment sector development in Vietnam[END_REF]. In India, COD accounts for 50-80% of online transaction payments [START_REF] Ernst | Rebirth of e-commerce in India[END_REF], while in the United Arab Emirates, this number is about 60% [START_REF] Hamid | Cash on delivery: The biggest obstacle to e-commerce in UAE and region[END_REF]. However, although it has gained more popularity in the last few years, little empirical research has investigated the reasons that influence customers' intention to adopt this method of payment or what factors make customers favour COD over other methods. This research aims to fill this gap by developing a model of factors that might influence the customers' intention to use this method. It is worth mentioning that no previous empirical research study exists, which makes it impossible to compare these results with previous research. However, the predicted factors were revealed in a prior literature review but in a different context, which was used in this study to predict whether these factors are the reasons that motivate customers to accept it as an alternative to existing e-payment methods. In other words, this research suggested that the concerns that make customers reluctant to adopt e-payment methods are predicted to be the motivating factors for adopting COD for e-commerce transaction payments.

The remainder of the paper is organized as follows: Section two provides a literature review on e-commerce payment methods and related concerns, which led to developing the current research model and hypothesis. Section three describes the employed research method. Section four presents the research results. Section five provides a discussion and the practical implications followed by the research conclusion.

2

Literature review

An electronic payment (e-payment) is a payment that is initiated, processed and received electronically over the Internet. Multiple methods of e-payment are used for ecommerce transactions, such as credit cards, prepaid cards or smart cards, e-cash (digital cash) and e-checks (digital checks). Among these, the credit card method is considered the most common e-payment method [START_REF] Kou | Payment technologies for e-commerce[END_REF]. According to much previous research, perceived privacy, security and trust were the main critical factors or reasons that make customers reluctant to adopt existing e-commerce and e-payment methods [START_REF] Barkhordari | Factors influencing adoption of e-payment systems: an empirical study on Iranian customers[END_REF][START_REF] Bolt | The effect of transaction pricing on the adoption of electronic payments: A cross-country comparison[END_REF][START_REF] Daştan | Factors affecting the adoption of mobile payment systems: An empirical analysis[END_REF][START_REF] Hamid | A risk perception analysis on the use of electronic payment systems by young adults[END_REF][START_REF] Kim | An empirical study of customers' perceptions of security and trust in e-payment systems[END_REF][START_REF] Lee | An analysis and comparison of different types of electronic payment systems[END_REF][START_REF] Lim | Exploring the reasons for a failure of electronic payment systems: A case study of an Australian company[END_REF][START_REF] Ozkan | Facilitating the adoption of e-payment system: Theoretical constructs and empirical analysis[END_REF]. E-payments generate information that can be used to analyse customer purchasing behavior or to conduct other investigations, which can be used for purposes that violate customers' privacy. Chellappa [START_REF] Chellappa | Consumers' trust in electronic commerce transactions: The role of perceived privacy and perceived security[END_REF] defined perceived privacy as the 'the subjective probability with which consumers believe that the collection and subsequent access, use, and disclosure of their private and personal information is consistent with their expectations' (pp. 12). Dinev, Xu, Smith, and Hart [START_REF] Dinev | Information privacy and correlates: An empirical attempt to bridge and distinguish privacy related concepts[END_REF] defined it as 'an individual's self-assessed state in which external agents have limited access to information about him or her' (p. 299). Customers might have more control of their privacy when they use COD as a payment method because they do not have to release too much information about themselves and their purchases. Banks and e-commerce websites are unable to track the history of their cash transactions. The customers simply need to provide their mobile phone numbers to receive the product at any location (e.g., at work, at home or in any public place) to protect their privacy and avoid tracking. In contrast, when a customer uses a credit card, every single transaction is recorded; banks, merchants or third parties can obtain this information and compile data about consumer purchasing behaviours, interests or preferences, which is an invasion of customer privacy for (Reference removed).

Security is still a consistent concern that prevents customers from engaging in ecommerce. Perceived security can be defined as 'the subjective probability with which consumers believe that their personal information (private and monetary) will not be viewed, stored, and manipulated during transit and storage by inappropriate parties in a manner consistent with their confident expectations [START_REF] Chellappa | Consumers' trust in electronic commerce transactions: The role of perceived privacy and perceived security[END_REF]. The COD method provides customers with a more convenient way not only to ensure the security of their payment, as they do not have to release their credit cards online, but also to inspect the quality of the product itself at the time of delivery so they can confirm they have received the same product that they ordered, which also helps to build trust between the customer and the e-commerce company. In this situation, as opposed to an online payment transaction, two processes are checked and ensured: receiving the product as expected, which helps to build trust, and payment by cash, which gives the feeling of security and eliminates the Internet's risks/threats. Obviously, this method provides advantages over payments transmitted over the Internet (online payment methods).

Distrust might exist in e-commerce contexts as there is no direct face-to-face interaction between the seller and buyer and uncertainty exists all the time because of both parties' unpredictable actions and opportunistic behaviours [START_REF] Jang | The consequences of customer trust and the determinants of purchasing intention in Internet shopping malls[END_REF]. Therefore, the key to removing this type of uncertainty and making successful e-commerce transactions is avoiding opportunistic behaviour [START_REF] Hosmer | Trust: The connecting link between organizational theory and philosophical ethics[END_REF], a situation that can be enabled through COD because the payment is made after the customer has received and inspected the ordered item. As pointed out by Li, Kim, and Park [START_REF] Li | The effects of Internet shoppers' trust on their purchasing intention in China[END_REF], trust can only exist if the consumer believes that the seller has the ability to provide and deliver goods of expected or better quality, which can be easily verified though COD payment.

Because of all these concerns that exist regarding online payments for e-commerce transactions, COD payment has been increasingly popular in the last few years in some countries, such as India, Gulf Cooperation Council (GCC) countries, Thailand, Vietnam, and Poland [START_REF]E-commerce and delivery: A study of the state of play of EU parcel markets with particular emphasis on e-commerce[END_REF][START_REF] Hamid | Cash on delivery: The biggest obstacle to e-commerce in UAE and region[END_REF][START_REF]E-and m-commerce and payment sector development in Vietnam[END_REF][START_REF] Nair | Will COD kill the Indian e-commerce star? Retrieved from[END_REF][START_REF] Rouibah | Electronic payment systems use and satisfaction in an Arabic country: Evidence from Kuwait[END_REF]. The aforementioned e-commerce concerns can be predicted to be the same factors that motivate customers to adopt COD. In other words, a customer feels that he is not vulnerable to any security threats, privacy invasions or opportunistic behaviours when he uses COD payment for e-commerce transactions. Thus, the following hypotheses are expected: H1. Perceived security will positively influence the customer's intention to adopt COD for e-commerce payment transactions.

H2. Perceived trust will positively influence the customer's intention to adopt COD for e-commerce payment transactions.

H3. Perceived privacy will positively influence the customer's intention to adopt COD for e-commerce payment transactions.

Research Method

The aim of this paper was to predict and test the factors that influence customers' intention to use COD for e-commerce payment transactions. Thus, three hypotheses were formulated, as presented in the previous section. A questionnaire instrument was designed that included the constructs shown in Table 1. All items were assessed using a five-point Likert scale (I strongly agree (5), I agree (4), Neutral (4), I disagree (2) and I strongly disagree (1)). The questionnaire was distributed to 100 participants from UAE. In total, 88 participants filled out and returned the survey, and their responses were deemed appropriate for analysis. The data were analysed using partial least squares (PLS) [a form of structural equation modelling] with SmartPLS software. PLS-SEM has experienced increasing dissemination in recent years in a variety of fields, including Information Systems [START_REF] Hair | A primer in partial least squares structural equation modeling (PLS-SEM)[END_REF]. PLS is typically recommended in situations in which there are no stable, well-defined theories to be tested in a confirmatory research setting, when the objective is prediction and when the sample size is small [START_REF] Chin | The partial least squares approach to structural equation modeling[END_REF][START_REF] Chin | Structural equation modeling analysis with small samples using partial least squares[END_REF][START_REF] Haenlein | A beginner's guide to partial least squares analysis, Understanding Statistics[END_REF][START_REF] Hair | A primer in partial least squares structural equation modeling (PLS-SEM)[END_REF][START_REF] Urbach | Structural equation modeling in information systems research using partial least squares[END_REF]. For all these reasons, PLS was an appropriate approach for the purpose of the current research. The model of factors and relationships (depicted in Figure 1) was developed based on conceptual research, yet there is no established theory to explain the factors that influence the customers' intention to adopt COD for ecommerce payment transactions. The model contains constructs that were not previously tested in the context of using COD for e-commerce payment transactions. In addition, the sample size was appropriate for the PLS technique. Furthermore, the condition of minimum sample size was met, as Chin [START_REF] Chin | The partial least squares approach to structural equation modeling[END_REF] and Hair et al. [START_REF] Hair | A primer in partial least squares structural equation modeling (PLS-SEM)[END_REF] proposed, in which the minimum sample size should be 10 times the largest number of structural paths directed at a particular latent construct in the structural model. The research model (Figure 1 or 2) has only one dependent (latent) variable, 'adoption of COD', which has three paths directed to it. Thus, the sample size of this study should be a minimum of 30, and this condition has been met (the sample was 88). As shown in the questionnaire and research model (Figure 2), the constructs were measured by a small number of items (n=2 or 3) where, for example, the intention to adopt COD is measured with one overall reflective item. However, as pointed out by Hair et al. [START_REF] Hair | A primer in partial least squares structural equation modeling (PLS-SEM)[END_REF], PLS-SEM can easily handle reflective and formative measurement models, as well as single-item constructs, with no identification problems or additional constraints. In addition, it is a good way to shorten the questionnaire.

Table 1. Survey Constructs and Measurements

Construct

Code Item

Security

SE1

I feel that my private information is secure when I use COD for e-commerce payment transactions.

SE2

When I use COD, I am not vulnerable to any internet security threats.

Privacy

PR1

COD keeps my identity anonymous so that banks and other third parties cannot track me.

PR2

My sensitive information can be protected when COD is used for e-commerce payment transactions.

PR3

COD reduces the amount of personal information that I need to share with e-commerce websites.

Trust TR1

COD gives me the chance to check/test the product before I make the payment.

TR4

COD ensures the identity of the e-commerce company.

Adoption of COD AD1

I intend to use COD when I purchase products from ecommerce websites.

Results Analysis

This section assesses the measurement and structural equation models.

Measurement Assessment

The measurement model was assessed using reliability and convergent and discriminant validity. Reliability was tested using Cronbach's alpha. According to Hair et al. [START_REF] Hair | a) Partial least squares structural equation modeling (PLS-SEM): An emerging tool in business research[END_REF][START_REF] Hair | Multivariate data analysis[END_REF], items have high reliability if the Cronbach's alpha value is greater than 0.7.

As shown in Table 2 (fourth column), the Cronbach's alpha value of all the constructs was greater than 0.7, so they had high reliability. The convergent validity was assessed by factor loadings, composite reliability and average variance extracted (AVE). The loadings for all items exceeded the recommended value of 0.6 (Table 2 and Figure 2). All of the constructs exceeded the threshold for composite reliability, as they were greater than 0.70 [START_REF] Hair | a) Partial least squares structural equation modeling (PLS-SEM): An emerging tool in business research[END_REF][START_REF] Hair | Multivariate data analysis[END_REF] (Table 4), ranging from 0.885-1.000. All values of average variance extracted were higher than 0.5 (Hair et al. [START_REF] Hair | Multivariate data analysis[END_REF], with a range from 0.855-1.000.

Table 2. Summary of Construct and Validity and Item Loading

Discriminant validity was assessed by examining whether the square root of the AVE for each construct was higher than the squared correlation between that construct and all other constructs [START_REF] Fornell | Evaluating structural equation models with unobservable variables and measurement error[END_REF]. Table 3 shows that discriminant validity was met. The square root of the AVE for each construct was greater than the correlation between constructs. As a result, the measurement model demonstrated adequate reliability, convergent validity and discriminant validity.

Structure Equation Model

Two measures were used to assess the structural model: the statistical significance (ttests) of the estimated path coefficients and the ability of the model to explain the variance in the dependent variables (R square). The R square attempts to measure the explained variance of the dependent variable relative to its total variance. Values of approximately 0.670 are considered substantial; values around 0.333 are moderate, while values of approximately 0.190 are weak [START_REF] Chin | The partial least squares approach to structural equation modeling[END_REF]. As shown in Figure 2, the R square of the research model was 0.823, indicating that 80% of the variance in the adoption of COD for e-commerce was explained by the independent variables, which is a high variance. Figure 2 shows the R square for the dependent variable (adoption of COD for e-commerce). To test the significance of the hypotheses, the rule proposed by Martinez-Ruiz and Aluja-Banet [START_REF] Martinez-Ruiz | Toward the definition of a structural equation model of Patent Value: PLS Path Modelling with Formative Constructs[END_REF] was followed. A t-value >1.65 is significant at the 0.05 level, while a t-value >2 is significant at the 0.01 level. Table 4 and Figure 3 show the t-value for each hypothesis. The research results indicated that perceived security, perceived privacy and perceived trust demonstrated a significant influence on the intention to adopt COD for e-commerce payment transactions. Therefore, H1, H2 and H3 were supported. However, it is obvious that H2 has the lowest significance t-value and this might be interpreted as some of the participants know the e-commerce websites that they deal with so they are adopting COD not mainly because of distrust but for security and privacy reasons.

Research Implications and Conclusion

This paper aimed to predict the factors that influence customers' intention to adopt COD as a method of payment for e-commerce transactions. As expected, the perceived security was a significant factor that motivated customers to adopt COD for ecommerce payment transactions. Since Internet security threats continue to increase and there are no guaranteed solutions, some customers still prefer to pay in cash at the time of delivery instead of taking the risk of using a credit card or other payment method over the Internet. Our results indicated that customers intend to adopt this method of payment and might prefer it to other e-payment methods. Thus, considering the results, e-commerce companies need to provide this service to customers and should also clearly indicate this option on their websites. For example, e-commerce companies could create a special logo that reflects the COD service and display this logo on their homepage to attract customers' attention and encourage them to purchase from the website.

Consistent with our predictions, perceived privacy had an impact on customer intention to adopt COD. Customers do not want to share too much information about themselves and would prefer to keep their identities anonymous when they conduct transactions online. They believe that this privacy can be obtained with a COD payment method. For the last few decades, e-commerce companies have failed to show respect for customer privacy by using their information, by annoying them with calls, texts or emails promoting products or services, or by following their personal life due to the ability to track every single purchase made using a credit card transaction.

As expected, customers perceive e-commerce websites as more trustworthy when COD is used as they can verify whether the item is exactly as they expected before purchasing it. Consumers do not have this advantage when they make a payment using a credit card in advance of receiving the ordered item. Customers might have negative past experiences with e-commerce websites, such as receiving incorrect, fake or unexpected products, so COD offers a solution as it enables them to verify if the ecommerce company is credible and trustworthy.

This paper is considered original because it is the first academic paper to the author's knowledge that empirically investigated the COD payment method for ecommerce transactions from a customer's perspective. COD could continue to grow as an e-commerce payment method because it offers an alternative to other e-payment methods, which have many problems, including security, privacy risk and credibility and other issues. COD could be one of the best options for certain customers in specific situations, but it should be accepted along with other traditional e-payment methods. It is not advisable to rely only on COD as there might also be customers who prefer the convenience of other methods and are concerned about COD for reasons such as cash availability and exchange issues.

For practitioners in the e-commerce industry, this study provides e-commerce companies with statistical data that show a customer preference for paying using COD. It also indicates the reasons that prompt them to adopt this method. Ecommerce companies have two options to tackle these reasons: 1) accepting COD besides other methods of e-payment. 2) Providing solutions that address the concerns and problems regarding existing traditional e-payment methods, including security, privacy and trust issues, which are not yet 100% guaranteed. Thus, option 1 could help e-commerce companies increase sales and convince customers to pay online. It also might give e-commerce websites that accept this method of payment an advantage over others that do not.

One limitation of this study is that it tested only three main constructs. There could be other constructs, such as cost, convenience and simplicity, that impact a customer's decision to adopt this method of payment for e-commerce transactions. Thus, future research might consider empirically testing other factors. Second, the data were collected from a context where around 40% of e-commerce transactions involved COD, and the results supported our prediction that three constructs influenced customers' intention to adopt COD. However, if data were collected from other contexts and countries where this method has not been used or is rarely accepted by e-commerce websites, the results might differ. Thus, further investigation of these constructs and hypotheses in a different context can help to generalize the results. Finally, it is not known whether the questionnaire respondents had prior experience purchasing products and paying online using a credit card, using COD, using both methods, or using none of them. Therefore, the research findings might be different for consumers who have never purchased online using a credit card, for example.

The current study predicted factors that influenced the adoption of COD from the customers' perspective. Future research will be required to investigate empirically if e-commerce companies are also willing to accept COD payments and what reasons might motivate them to do so. Future research is also needed to identify whether using COD will enable e-commerce companies to gain a competitive advantage and increase sales over other e-commerce companies that do not accept this payment method.

Fig. 1 .

 1 Fig. 1. Proposed Theoretical Model with Hypotheses

Fig. 3 .

 3 Fig. 3. Factors' Relationship with the Adoption of COD by t-values Using SmartPLS (the level of significance is indicated by bold arrow

Table 3 .

 3 Correlation between Constructs (the diagonal represents the square roots of average variance extracted)

		Adoption	Perceived	Perceived	Perceived
		of COD	Privacy	Security	Trust
	Adoption	1.000
	of COD
	Perceived	-0.667	0.895
	Privacy
	Perceived	-0.870	0.894	0.891
	Security
	Perceived	0.251	-0.004	-0.108	0.925
	Trust

Fig. 2. PLS Structural Equation Mode (with factor loading values)

Table 4 .

 4 Hypothesis Testing Based on t-values -value >1.65 is significant at the 0.05** level; a t-value >2 is significant at the 0.01* level.

	H No.	Hypothesis	t Statistics	Significance
	H1	Perceived Security>	18.433	Supported
		Adoption of COD
	H2	Perceived Trust ->	2.256	Supported
		Adoption of COD
	H3	Perceived Privacy ->	8.553	Supported
		Adoption of COD
	Note: A t