| Abstract: | The impact on concentration of advertising and other variables is examined in a multiple regression model. The findings indicate that the positive influence of advertising observed for earlier periods continued during 1972–1977. By testing hypotheses suggested by other researchers, this paper resolves most, if not all, of the seemingly conflicting findings of researchers examining changes in concentration since 1963. The findings also strongly suggest that lagged models provide little, if any, added insight into the causes of changes in concentration. |
