Abstract
The 662 firms of manufacturing have already been studied on ex post evaluation of returns on plant & equipment and software (P & E/S) investments. However, the return on research and development (R/D) expense, being often larger than P & E/S investment, has not been studied. Especially, the study on R/D is not avoidable for pharmaceutical firms having huge R/D expense. Then, the 3 variable model of P & E/S/R & D investment expanded from 2 variable model of P & E/S, is applied to the analysis on 25 major pharmaceutical firms
