This paper considers whether the results of Steurs (1995) hold under differentiated oligopoly with quality−improving R&D when firms play the role of Bertrand player, focusing on the choice of optimal R&D policy. When making comparisons of market performances among three cases (e.g. R&D competition, intra−industry R&D cooperation and inter−industry R&D cooperation), we show that the optimal R&D policy depends on the relationship between intra− and inter−industry spillovers as well as the level of spillovers and product differentiation. Therefore, the government must coordinate the policy according to the level of spillovers and product differentiation after the government has probed the relationship thoroughly.
本稿は2005年度日本経済学会秋季大会での報告論文「産業間スピルオーバー存在下の品質改善型 R&D 投資」を加筆修正したものである。