DAMAGE CONTROL PRODUCTIVITY - WHY ECONOMETRICS MATTERS

For nonexperimental data, asymmetric specifications of the role of dam age control inputs impose restrictions of homotheticity or nonjointnes s on the underlying technology. A generalized symmetric form where dam age control inputs affect factor diminution functions motivates use of symmetric specifications. Panel data and estimation methods are prese nted to produce robust estimates of damage control productivity that a re free of heterogeneity bias. Estimates of the productivity of pestic ides for French cereal farm production illustrate that fixed firm and time effects are important. Estimates indicate substantially smaller m arginal productivity of pesticides than reported by past studies.