Public and Private Capital Productivity Puzzle: A Nonparametric Approach

Is public expenditure productive? Is there a shortfall or excess in public capital investment? We address these old issues in the light of new econometric tools. It is argued that the Cobb-Douglas specification that ignores nonlinearity inherent in the functional relationship of the production technology causes incorrect estimates of input elasticities. To avoid possible model misspecification, we use Li-Racine generalized kernel estimation. This procedure is used to estimate the returns to private capital, employment, and public capital in gross state product from a panel of 48 states for 17 years. In contrast to previous studies, we find that the return to public capital is positive and significantly different from zero.