保固維修是服務重要的一環，它可以展現公司對產品負責任的態度及承諾，保固維修也是消費者在消費過程中的重要指標。然而，當廠商將此服務委託外包給服務代理商時，由於資訊不對稱，保修供應商不清楚產品損壞的情況，因此容易產生服務代理商高報成本等的保修詐欺問題。 本研究使用賽局理論建立服務代理商和保修供應商互動的數學模型。在此數學模型中，保修供應商為了避免服務代理商謊報，會制定審查率及罰款比例。由於服務代理商的目的是將收益最大化，而保修供應商必須將成本最小化，在這兩個前提下，本研究需找出均衡解，以減少詐欺問題。本研究建立兩個模型，第一個模型使用擴展形式賽局（extensive-form game）建模求解，並使用數值範例探討懲罰率不同對均衡解的影響；第二個模型使用重複賽局理論，建立一個可以將服務代理商的累犯行為納入考量的審查機制，並加入誠實的服務代理商，以討論當誠實代理商存在時，均衡解會如何改變，以確保模型更能貼近實際情況。研究結果之均衡解可以提供保修供應商當做未來建立保固合約的依據參考，也能協助供應商評估未來保修服務的預算，以及建立更完善的審查機制。

Warranty is an important part of service. It can be used to demonstrate a company's commitment to its products, and is also considered an important indicator for consumers in making purchase decisions. However, when a manufacturer outsources the warranty service to external service agents, service agents may conduct warranty frauds such as adding cost elements to existing service claims due to information asymmetry between warranty providers and service agents. This study uses game theory to build a mathematical model for formulating the interaction between service agents and warranty providers. In order to reduce the number of service frauds, the warranty provider need to set a rate of claim validation and a rate of penalty. An equilibrium involving these key decision variables can then be derived under the conditions that the service agent tries maximizing its profit and the warranty provider tries minimizing its cost. Two different models were developed in this study. The first model uses extensive-form game to formulate the problem and solve for the equilibrium, and uses numerical examples to discuss the impact of penalty rates on equilibrium. The second model uses repeated-game formulation to take the service-agent's reputation into consideration. In the repeated-game model, we also discuss how the equilibrium solution will change when honest agents exist. Research results of this study can provide some guidelines for the warranty provider to design new warranty contracts in the future. They can also help the warranty provider to develop a more comprehensive validation mechanism under budget constraints.

Alexander, C., & Feinstein, J. S. (1987). A microeconometric analysis of income tax evasion and its detection. Massachusetts Institute of Technology. Unpublished manuscript.
Allingham, M. G., & Sandmo, A. (1972). Income tax evasion: a theoretical analysis. Journal of Public Economics, 1(3-4), 323-338.
Alm, J., McClelland, G. H., & Schulze, W. D. (1992). Why do people pay taxes? Journal of Public Economics, 48, 21-48.
Ambad, P. M., & Kulkarni, M. S. (2013). A methodology for design for warranty with focus on reliability and warranty policies. Journal of Advances in Management Research, 10(1), 139-155.
Carfì, D., & Musolino, F. (2015). Tax evasion: a game countermeasure. Atti della Accademia Peloritana dei Pericolanti-Classe di Scienze Fisiche, Matematiche e Naturali, 93(1), 2.
Chang, Y.-T. (2020). Game Theoretic Analysis of Service Agent Warranty Fraud, Master Thesis, National Taiwan University of Science and Technology.
Chen, K. P., & Chu, C. C. (2005). Internal control versus external manipulation: A model of corporate income tax evasion. rand Journal of Economics, 151-164.
Chu J., & Chintagunta P. K. (2011). An empirical test of warranty theories in the US computer server and Automobile markets, Journal of Marketing, 75(2), 75-92.
Chyz, J. A., Leung, W. S. C., Li, O. Z., & Rui, O. M. (2013). Labor unions and tax aggressiveness. Journal of Financial Economics, 108(3), 675-698.
Clotfelter, C. T. (1983). Tax evasion and tax rates. The Review of Economics and Statistics, 65(3), 363-373.
Crocker, K. J., & Slemrod, J. (2005). Corporate tax evasion with agency costs. Journal of Public Economics, 89(9-10), 1593-1610.
Dyreng, S. D., Hanlon, M., & Maydew E. (2018). When does tax avoidance result in tax uncertainty. The Accounting Review, 94(2), 179-203.
Gianini, G., Fossi, L. G., Mio, C., Caelen, O., Brunie, L., & Damiani, E. (2020). Managing a pool of rules for credit card fraud detection by a Game Theory based approach. Future Generation Computer Systems, 102, 549-561.
Goumagias, N., & Hristu-Varsakelis, D. (2013). Tax evasion by risk-averse firms in Greece: a discrete Markov-based optimization model. A Journal of Mathematical Programming and Operations Research, 62(8), 1153-1167.
Greenberg, J. (1984). Avoiding tax avoidance: A (repeated) game-theoretic approach. Journal of Economic Theory, 32(1), 1-13.
Guenther, D. A., Wilson, R. J., & Wu, K. (2019). Tax uncertainty and incremental tax avoidance. The Accounting Review, 94(2), 229-247.
Hossain, M. S., & Al Mahmud, M. A. (2012). Customers’ Attitude towards Product Brand and Warranty/Guarantee option: An Empirical Study on Electronic Products User in Dhaka City in Bangladesh. Global Advanced Research Journal of Management and Business Studies, 1(5), 158-162.
Huysentruyt, M., & Read, D. (2010). How do people value extended warranties? Evidence from two field surveys. Journal of risk and uncertainty, 40(3), 197-218.
Kurvinen. M., Toyryla, I., & Murthy, D. N. P. (2016). Warranty fraud management: reducing fraud and other excess costs in warranty and service operations. John Wiley & Sons.
Landsberger, M., & Meilijson, I. (1982). Incentive generating state dependent penalty system: The case of income tax evasion. Journal of Public Economics, 19(3), 333-352.
Lin, C.-Y., Kuo, T.-H., Huang, Y.-C., Lin, C., & Ho, L.-A. (2007). The warranty policy under fuzzy environment. International Journal of Quality & Reliability Management, 24(2), 191-202.
Murthy, D., & Djamaludin, I. (2002). New product warranty: A literature review. International Journal of Production Economics, 79(3), 231-260.
Murthy, D., & Jack, N. (2017). Game theoretic modelling of service agent warranty fraud. Journal of the Operational Research Society, 68(11), 1399-1408.
Najmi, A., Haq, M. A., Majeed, S., & Khan, N. R. (2014). Effects of product’s warranty on customers’ preferences: empirical findings on reverse logistics models. Scientific Journal of Logistics, 10(3), 305-317.
Rabin, M. (1993). Incorporating Fairness into Game Theory and Economics. The American Economic Review, 83(5), 1281-1302.
Rego, S. O., & Wilson, R. (2012). Equity risk incentives and corporate tax aggressiveness. Journal of Accounting Research, 50(3), 775-810.
Reinganum, J. F., & Wilde, L. L. (1986). Equilibrium verification and reporting policies in a model of tax compliance. International Economic Review, 27(3), 739-760.
Sanchez, I., & Sobel, J. (1993). Hierarchical design and enforcement of income tax policies. Journal of public economics, 50(3), 345-369.
Shackelford, D. A., & Shevlin, T. (2001). Empirical tax research in accounting. Journal of accounting and economics, 31(1-3), 321-387.
Slemrod, J., & Yitzhaki, S. (2002). Tax avoidance, evasion, and administration. Handbook of Public Economics, 3, 1423-1470.
Srinivasan, T. N. (1973). Tax evasion: A model. Journal of Public Economics, 2, 339-346.
Srinivasana, R., Manivannanb, S., Ethirajc, N., Devid, S. P., & Kirane, S. V. (2016). Modelling an Optimized Warranty Analysis methodology for fleet industry using data mining clustering methodologies with Fraud detection mechanism using pattern recognition on hybrid analytic approach. Procedia Computer Science, 87, 322-327.
Teng, S. G., Ho, S. M., & Shumar, D. (2005). Enhancing supply chain operations through effective classification of warranty returns. International Journal of Quality & Reliability Management, 22(2), 137-148.
Yitzhaki, S. (1974). A note on income tax evasion: A theoretical analysis. Journal of public economics, 3, 201-202.