DISCUSSION.

The article focuses on four research papers by various economists, which deal with "investment" with different points of departure. R. Eisner deals with the more general estimation problem encountered in investment functions; Frederick M. Scherer investigates performance of investment under different market structures; Edwin Mansfield explores the characteristics, costs, trade-offs of research and development, and the diffusion process of an innovation; and Jora R. Miniasan concentrates on estimating rate of return to research and development expenditures. Scherer tests a few alternative hypotheses relating to the stability of investment and the structure of the industry. He finds that the variability of investment is correlated, among others, with concentration ratios, which is taken to indicate the market structure. Miniasan has made two comments, one dealing with the choice of the dependent variable and the other relating to the, interpretation of the results. The main results are derived from information collected by survey and opinion sampling.