個體經濟學的三個議題

Abstract

本論文包含三個議題。 第一篇文章題目是「賣家的網路拍賣展售策略」。這篇文章提出了一個理論框架，刻劃賣家的網路拍賣展售策略，結果顯示，賣家的拍賣策略會被他與買家的相對時間折現率所決定。具體而言，固定價格展售、傳統拍賣、直接購買價拍賣都可能是最佳策略。時間不折現的賣家遇到時間不折現的買家時，他會採取傳統拍賣；在其他其況下，若賣家相對買家的時間折現率中等，他將會採用直接購買價拍賣，而最沒有耐心的賣家會採取固定價格展售。若賣家比買家更沒有耐心，那麼不同賣家的最佳保留價格將與賣家的時間偏好率成逆向關係，這結果在不同展售形式或者在單一展售型式比較下都是正確的。因此，固定展售的標價高於直接購買拍賣的保留價格，後者又高於傳統拍賣的保留價格。這樣的理論結果有非常清晰的實證預測，擬合了我們觀察的數據。 第二篇文章題目是「相關資訊下的主觀表現評價」。本篇在一個靜態主雇模型下探討最適契約的性質。我們假定主雇雙方看到的二元訊號是相關的。結果顯示，最適契約有三種型式。第一種與 MacLeod (2003) 結果平行，代理人的酬勞取決於雇主的訊號，而雇主的支付與雙方訊號皆有關係；第二種與第一種模型對稱，雇主的支付取決於代理人的訊號，而代理人的酬勞由雙方訊號共同決定。在前兩種契約型式中，都有某一方的支付或酬勞完全取決於對方訊號的其況，而他自己的訊號則僅僅用來防止對方誤報結果。第三種契約完整使用了雙方的訊號，亦即，雙方的支付或酬勞由雙方訊號共同決定。此外，若雇主越能提高代理人的努力程度，第一種契約越容易出現。 第三篇文章評論 MacLeod (2003) 的著名研究「主觀評價的最適契約」，在更一般的資訊結構下，聚焦於燒錢問題，亦即，雇主的支付與代理人所得的酬勞不一致。本文指出， MacLeod 的論證有誤，並提出一個反例（最適契約毋須燒錢）。最後，我提出一個充分條件，讓燒錢成為本質上會出現的結果。

This dissertation consists of three essays in microeconomics. This fist essay is entitled 'The Seller's Listing Strategy in Online Auctions', which proposes a unified framework to characterize the seller's optimal listing strategy as a function of the theirs rates of time impatience. Specifically, the fixed-price listing, the regular auction, and the buy-it-now auction are each a solution of the seller's single optimization problem under different values of the relative rate of time impatience: The perfectly patient seller adopts the regular auction when facing perfectly patient bidders; for the other cases, the sellers with medium range of time-impatience adopt the buy-it-now auctions; and the most impatient sellers adopt the fixed-price listing. Moreover, if the seller is more impatient than the bidders, the reverse price is inversely related to the value of the seller's discount factor, either within or across formats. This in turn implies that the posted price in the fixed-price sale is greater than the reserve price of the buy-it-now auction, followed by that of the regular auction. These predictions offer clear empirical implications, which accommodate our data. The second essay is entitled 'Subjective Performance Evaluation with Correlated Information'. This essay revisits the property of the optimal contract of a static principal-agent model with subjective performance evaluations. Assume that the principal and the agent receive correlated binary-signals. It is shown that, the optimal contract falls into three types. In the first type, which parallels MacLeod's (2003) result, the agent's compensation depends on the principal's signal only, while the latter's wage cost depends on the signals of both parties. The second type is symmetric to that of the first: the agent's compensation depends on the signals of both parties, while the principal's wage cost depends only on the agent's signal. In the first two types, although one party's pay (or cost) depends only on the other party's signal, his own signal is nonetheless used as an instrument to prevent the other party from strategically misreporting. The third type fully utilizes both parties' information, that is, both parties' payoffs depend on both parties' signals. Moreover, we can show that, as the implemented effort level increases, the first type of the contract tends to prevail. The third essay is a comment on the famous study 'Optimal Contracting with Subjective Evaluation' (MacLeod 2003). This essay concentrates on the topic of money burning under the more general information structure. MacLeod argues that money burning always holds if the implemented effort level exceeds the minimum. In this essay, I point out his argument is invalid. I give one counter-example against this result. Moreover, I give a sufficient condition, which generically holds, such that the existence of money burning is established.