Before 1933, the price analysis was studied under two market models:
In perfect competition model, it was assumed that there were large number of firms producing homogeneous products. In the case of monopoly, there was only one seller of a product. Both these models were thus polar extremes and were considered satisfactory for the market price analysis in economic theory.
In the year 1933, Mrs. Joan Robinson of Cambridge University in England and Edward Chamberlin of Harvard University in America introduced a third market model. It was called Imperfect Competition by Mrs. Joan Robinson and Monopolistic Competition by Chamberlin.
The third market model called monopolistic competition or imperfect competition contains larger elements of competitive model and a fewer elements of monopoly model. It is thus a hybrid of monopoly and competition.