This article proposes a novel procedure to test whether firms compete à la Cournot or perfectly collude when firms' conduct is allowed to be heterogeneous along the conditional distribution of price–cost margins. We apply the procedure to a panel of quarterly data for 177 mobile-voice...

A large panel of regional UK data is used to provide detailed estimates of the direct and external effects of education and labour market experience on wages. The results offer strong evidence in support of the predictions of the endogenous growth theory (Lucas, 1988), where the - spatial or...