Degree Name

Doctor of Philosophy


Department of Economics


The contribution of agricultural R&D investment to productivity is recognized as one of the most important indicator for policy making in economic development. Several empirical studies of R&D evaluation have attempted to create an appropriate approach to calculate the rates of return to agricultural R&D investment. Although many approaches are used to evaluate agricultural R&D investment, none is superior in all situations. This study attempts to use a new approach, employing R&D knowledge stock and its depreciation, modem time series data analysis, and OLS method to calculate the rate of return to R&D investment, rather than R&D expenditures with specific lag structures and OLS estimation. This study applies the problem of rice productivity in Thailand as a case study. Thailand has a very low rice yield per hectare compared to other countries in Asia and throughout the world with similar agro-climate conditions and land endowments. The question is then how successful the continuing high yield has been, and what are its causes and effects. Rice R&D is focused whether it is a major determinant stimulating rice yield growth, and whether its allocation is far below the optimum level. Thus, the purpose of this study is to investigate the causes and effects of rice yield growth and to evaluate the contribution of R&D to rice yield.