不對稱資訊下雙產品獨占廠商最適定價機制選擇：序列定價與組合定價

The Optimal Design of Transaction-Based Discriminatory Mechanism: Sequential Schemes versus Optimal Bundling

科技的進展使得廠商可藉由消費者行為資訊進行差別取價，以提升獲利；目前已有許多文獻針對行為差別取價策略進行討論，但大多未利用線性訂價的方式，或僅考量單一產品。因此本文嘗試探討當一生產兩種產品（A 產品與B 產品）之獨占廠商，面對考量當期交易決策將如何影響未來交易條件之「策略性消費者」時，獨占廠商是否可藉由設計A、B 兩種產品的序列交易機制，利用前期消費者行為資訊，於後期提升對消費者類型的認知以進行行為差別取價來提升總獲利；並探討消費者結構對廠商最適訂價策略的影響。本文假設消費者可先依據對A、B 產品的需求強度分為對A、B 產品需求強度皆低之低端消費者、對A 產品需求強度低但對B 產品需求強度高之中端消費者，以及對A、B 產品的需求強度皆高的高端消費者，此三類消費者又皆有同一比例為策略性購買者，其餘則為短視近利購買者。本文以賽局分析的方法，假定廠商在對上述六型消費者資訊不完全下，且涵蓋B 產品市場所有範圍，以非線性訂價篩選消費者，獲致以下結果：(1)當市場上全為理性消費者時，消費者的策略性回應使得廠商無法藉由行為差別取價來提高獲利，廠商宜採產品組合交易機制。(2)當低端和中端消費者對A 產品的需求強度夠高時，隨著低端消費者比例越高，序列交易機制相較於產品組合機制越可能成為廠商的最適策略。因為此時市場結構以對A、B 產品需求強度為正相關的消費者為主，使得廠商可藉由序列交易機制而有效推論消費者對另一種產品的需求強度，並可利用差別取價的機會而提高獲利。(3) 廠商的最適序列交易機制設計為：第一期的合約設計必須能夠使短視近利高端消費者與理性高端消費者在自我選擇後，被區隔在不同的消費者分群。(4)假設當市場上全為短視近利消費者時，先販售B 產品的序列交易機制（以下簡稱序列B），不似產品組合，可使廠商藉由販售B 產品的資訊，獲得可針對A 產品進行差別取價的機會，因此當販售A 產品階段可對低端和高端消費者差別取價的利益大於犧牲中端消費者時，序列B 凌駕產品組合機制；而相較於序列A，當序列B 可利用對A 產品進行差別取價的優勢，來彌補其在B 產品部分對高端和低端消費者的價格劣勢時，廠商宜採用序列B。先販售A產品的序列交易機制（以下簡稱序列A）可使廠商藉由販售A 產品的資訊，在B 產品販售階段可對高端消費者進行一級差別取價、並對中低端消費者進行二級差別取價的機會，因此當序列A 在高端與低端消費者的B 產品價格優勢，能彌補在第一階段為了獲得資訊而無法販售A 產品給低端消費者的利潤損失時，廠商宜採用序列A。

The rapid development of technology increases the availability of customers’ transaction data, facilitating the practice of “behavior-based price discrimination.” This thesis investigates under what circumstances a monopolistic firm selling two products (A and B) should sell one product first in order to elicit customer information and then perform optimal screening based on that information when selling the other product, and when such a sequential transaction scheme is desirable, which product should be chosen to offer to customers first. In our model customers are privately informed about their valuations for the two products, which are known to the monopolistic firm to be positively correlated. The revelation principle in contract theory implies that from the firm’s perspective, no sequential transaction schemes can outperform the static optimal bundling strategy in this environment, if all customers are fully rational. This thesis, on the other hand, considers an environment where a positive fraction of the customers are myopic, who totally ignore the fact that their current transaction may reveal information to the firm and hence may impact on the terms of transactions that they may face when they purchase another product from the firm in the future. We show that the presence of myopic customers may result in a sequential transaction scheme outperforming the optimal bundling scheme, and hence the order in which the two products are sequentially sold matters in equilibrium. To simplify the analysis we assume that fully customers can be classified into three categories according to their valuations for the two products: the highs have high demand intensities for both products, the mediums have a low demand intensity for product A but a high demand intensity for product B, and the lows have low demand intensities for both products. The thesis produces the following results: (1) When the demand intensity of the lows and the mediums for product A is not too low, the likelihood that a sequential transaction scheme may outperform the optimal bundling scheme increases with the population o the lows. (2) A necessary condition for a sequential transaction scheme to outperform the optimal bundling scheme is that the former allows the firm to discriminate the rational highs from the myopic highs. (3) The optimal bundling scheme may continue to outperform any sequential transaction scheme in the event that all customers are myopic. (4) When a sequential transaction scheme outperforms the optimal bundling scheme, each product may be selected to offer to customers first; we identify a number of factors that affect the optimal choice of the selling order.