In the empirical analysis of financial time series, multivariate GARCH models have been used in various forms. In most cases it is not well understood how the use of a restricted model has to be paid with loss of valuable information. We investigate the structural implications of two alternative...

When the production of high quality needs the employment of qualified labour, firms' decisions concerning quality are affected by the extent to which skills are abundant. By means of a comparison between monopoly and perfect competition, we show how market power in such a context may entail a...