TECHSIM, a regional field crop and national livestock econometric simulation model, evaluates impacts of technological change Unlike other econometric models specified and constructed in an ad hoc fashion, TECHSIM makes practical use of theory by incorporating a priori information regarding the structure of the agricultural sectors modeled during estimation This procedure improves calculation of welfare gains or losses resulting from technological changes to agriculture The model provides policy-makers with detailed welfare answers, users need only supply changes in yields and variable production costs.