本研究以後悔理論探討電信服務契約轉換時間決策與轉換後結果之評價對契約轉換後悔程度。研究以 2x2因子實驗設計，針對具轉換電信服務契約經驗之消費者進行調查並獲得132份有效問卷進行單變量分 析。假設檢定分別為檢測轉換時間決策與轉換後結果之評價對後悔的直接效果、轉換時間決策與轉換後結 果之評價間交互作用對後悔的效果，以及決策合理性與知覺責任之干擾效果。分析結果顯示，契約轉換時 間決策與轉換後結果之評價對後悔皆具顯著效果；契約存在期間轉換之後悔程度較契約屆滿後轉換來得高; 而負面評價之後悔程度比正面評價要高。在交互作用方面，不論契約存在期間或屆滿後轉換，一旦產生負 面評價，後悔程度會比正面評價要高；契約存在期間或屆滿後轉換產生的負面評價在高決策合理性的情況 下，後悔程度會降低；反之在高知覺責任的情況下，後悔程度會越高。本研究擴展後悔理論之應用從消費 者對電信契約之消費決策至轉換決策，並提出一些有效行銷策略方案做為電信服務業之參考。

This study explores the effects of switch timing decisions and valence of the outcome on regret in a contract-based telecommunication service context by applying regret theory. A 2 x 2 factorial experiment was designed, which focused on the consumers who had experiences in switching telecommunication service contract. 132 respondents had participated in the survey and all collected data were analyzed by univariate analysis. Hypothesis testing was conducted to test the direct effect of switching timing and valence of the outcome on regret, the interaction effect of switching timing and valence of the outcome on regret, and the moderating roles of justifiability and perceived responsibility. The results indicated that switch timing and valence of the outcome had significant and direct effect on regret. With regard to the interaction effects, both switch within or after contract expiry, negative valence of the outcome had higher regret than positive outcome. In the condition of high justifiability, switch within or after contract expiry with negative valence of the outcome had lower regret than low justifiability; however, the regret was higher in high perceived responsibility than low perceived responsibility condition. This study provides some insights for extending the application of regret theory from consumption decisions to switching decisions, and some alternative approaches for effective marketing strategies for service providers.