本文係探討廠商的價格訂定策略。因消費者在購買商品之前需支付搜尋成本，所以廠商在消費者即將購買時可以套牢消費者。這是我們所熟知的人質問題 (hold up problem)。本文將以此觀點建構出新的訂價模型。廠商需在價格上做承諾才得以避免發生人質問題。這也提供了新的價格調整成本，可以解釋為何會有價格僵固的現象。本文特色在於發掘供給面或是需求面的變動對於價格訂定的策略及價格調整的頻率有了新的預測。例如，生產成本增加、搜尋成本下降、需求下降皆有助於價格調整頻率上升。最後，本文討論競爭對於定價的影響，此處與實證資料吻合；競爭越激烈價格調整越頻繁。

This paper examines the frequency of price adjustments with imperfect seller credibility in a static setting. Firms must commit to prices as a way to circumvent the potential hold up of consumers who face search costs. Infrequent price adjustments is a commitment mechanism against the potential hold-up problem. Conditions under which commitment to a single price is optimal are given. Firms adjust prices according to its cost when the potential cost is high, or when the search cost is small, or if the distribution of consumer reservation prices has a high hazard rate. The effects of product market competition are also analyzed. This paper provides a new source for the cost of adjusting prices.

Contents
1 Abstract 3
2 Acknowledgements 4
3 Introduction 5
4 A Monopoly Firm Model 8
4.1 Example with Uniformly Distributed Reservation Price . . . . . . . . . . . . . . . . . . . 23
4.2 Example with Exponential Distributed Reservation Price . . . . . . . . . . . . . 25
5 Multiple Firms and Product Market Competition 27
5.1Without Entry . . . ...... . . . 28
5.2With Entry . . . . . . 33
6 Conclusion 34
7 Appendix 36
8 Bibliography 38

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