| 摘要: | 本論文包含三篇與廠商研發活動相關。本論文採用代表性消費者模型，而且假設產品需求函數為線性。
相較於其他文獻強調對稱性，本文允許廠商具有垂直差異，換言之，較有效率的廠商反應較高的正初利潤(Positive Primary Markup)，而較沒有效率的廠商其正初利潤為較低。其次，透過兩階段品質賽局，第一階段廠商進行產品研發，可以提高正初利潤
第二階段進行產品競爭--包括數量競爭或價格競爭。除了探討純粹雙合(private duopoly)之外，第三章探討次佳解、第四章則以混合雙占為研究主題。
第二章強調數量競爭與價格競爭的比較。研究發現，數量競爭得到唯一解，而價格競爭可能得到多點解。
相較於價格競爭，效率較差的廠商在數量競爭較容易存活。文獻指出，數量競爭下的品質水準高於價格競爭，然而，當垂直差異夠大時，效率廠商可能發生品質排序逆轉的情形。就產出排序而言，效率廠商得到正常排序，即價格競爭下的廠商產出高於數量競爭
而效率較差的廠商，在數量競爭可能導致較高的產出。最後，利用程式模擬得到，沒有找到任何反例證明數量競爭導致較高的社會福利。
第三章假設在產品競爭時，廠商採取數量競爭。在第一階段，則想像存在一個社會計畫者透過決定品質水準極大化社會福利。研究得到，相較次佳解，效率較差的廠商在純粹數量競爭較容易存活。在次佳解下，效率廠商得到較高的產出與品質研發，而效率較差的廠商可能發生產出與品質研發逆轉的現象。其次，當均衡解為阻卻進入(Deterred-entry)時，政府無法透過研發補助(課稅)影響廠商的決策。當容許進入解(Accommodated-entry)或封鎖解(Blockaded-entry)出現時，對效率廠商進行研發補貼會提高社會福利，而對效率較差的廠商的補貼或課稅取決於不對稱程度。
第四章探討混合雙占下，公、民廠商的研發活動，並且與純粹雙占進行比較。研究得到，當民營廠商的效率程度夠高的話，則公營廠商的品質水準可能低於民營企業。在對稱之下，公營廠商的品質水準高於純粹雙占或民營廠商。相較於純粹雙占，混合雙占具有較高的社會福利，同時具有較高的產業產出、品質水準與較高的HHI(Herfindahl Index)。考慮最適私有化的問題，當私有化的程度越高，伴隨著較低的產業產出、品質水準與HHI。最適私有化程度與民營廠商的效率程正相關，而且最適私有化指出產業產出、品質水準、HHI等無法做為衡量社會福利的絕對指標。
This dissertation concludes three parts related to research and development(R&D) in an asymmetric duopoly. We use a representative-consumer model where the demands arise from a representative consumer's quasi-linear utility function, and each demand function is linear. The firms are allowed to be asymmetric: If the initial primary markup of a firm is higher than that of its rival, then it (its rival) is referred to as the more (less) efficient firm. Throughout three topics, we obtain that (1) the presence of R&D investment makes it harder for the less efficient firm to survive
(2) the more efficient firm has a normal output ranking
(3) equilibrium represents three types: blockaded-entry, deterred-entry and accommodated-entry equilibrium. The other results are as follows:
Part I, we compare the Cournot and Bertrand equilibria in a two stage duopoly game where, in the first stage, the firms compete in product R&D. Cournot competition entails a unique equilibrium, whereas Bertrand competition may yield two equilibria. Under each mode of competition, it is easier for the less efficient firm to survive under Cournot than under Bertrand competition. Two crucial results are established regarding firm size. First, Bertrand competition yields higher industry output than does Cournot competition. Second, compared with Cournot competition, Bertrand competition shifts production from the less to the more efficient firm. These crucial results, together with the known size effect, explain the following three results. First, the more efficient firm has a normal output ranking, whereas the less efficient firm may demonstrate an output reversal. Second, the more efficient firm may demonstrate a R\&D reversal, whereas the less efficient firm has a normal R&D ranking (its Cournot R&D effort exceeds its Bertrand R&D effort). Third, Bertrand competition would be more welfare-efficient than Cournot competition. Moreover, the more efficient firm may demonstrate a price reversal, whereas the less efficient firm has a normal price ranking.
Part II, we concern a Cournot duopoly game with two stages-the R&D first stage and the product-competition second stage. We aim at characterizing a second-best policy in which the social planner can control the first stage through R&D subsidies but cannot regulate the second stage. It is easier for the less efficient firm to survive under Cournot competition than under Second-best. A more efficient firm produces more output(engages in more R&D activity) under Second-best than under Cournot competition, whereas the ranking of output and quality of a less efficient firm may reversal. When blockaded-entry strategy prevails, subsidization of efficient firm improves social welfare
whereas deterred-entry strategy prevails, subsidization can not achieve the socially second-best equilibrium. When accommodated-entry strategy prevails, subsidization of efficient firm always improves social welfare. However, subsidization or taxation of less efficient firm depends upon asymmetric degree.
Part III, we characterize the equilibria in a two stage mixed duopoly game where firms compete each other in the first stage of engagement in R&D activity and in the second stage of Cournot competition. The result demonstrates that public firm may engage in less R&D activities than private firm only if private firm is sufficiently efficient. Compared with private duopoly or mixed duopoly with an efficient private firm, mixed duopoly with an efficient public firm yields higher social welfare, which is correspondent to higher criteria, including total output, total R&D level, Herfindahl index. Under partial privatization of mixed duopoly with an efficient public firm, we find that those criteria decrease with increasing degree of partial privatization. With increasing efficiency of private firm, optimal degree of partial privatization increases and it may cause lower criteria compared to mixed duopoly with an efficient public firm. |
