In this paper we argue that some empirical specifications may not be appropriate to estimate accurately the returns human capital. particular, show inclusion in aggregate production functions of ratio skilled labor force over total as a proxy for capital good way control heterogeneity labor.

abstract some issues such as dehydration, local and chronological disproportion of rainfall, low productivity of water in agricultural sector, increasing demand for agricultural products due to increase in population participate with doughtiness are the most challenges of agricultural water. these factors caused water to be as one of the important and scarce inputs is agricultural products. the...

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an indirect tarns-log production function was employed to estimate the demand functions for such inputs as: fertilizer, seed, pesticide, water recourse and machinery as subject to budget constraint and while using data related to cotton producers in the three provinces of north khorasan, khorasane razavi, and south khorasan in 2007-8. lagrange coefficients with relation to cotton producers in t...

throughout the current study, the appropriate function for a description of egg production curve in a commercial broiler dam line was determined through fittings of a number of six mathematical models, namely: incomplete gamma function (wm): modified incomplete gamma function (mwm): compartmental function (cm): modified compartmental function )mcm): polynomial regression function of ali and sch...

abstract different strategies are existed for adjusting with water shortage, of which the strategy of suitable policies adoption by determining optimum production function can be mentioned. water shortage and quality degradation of soil and water resources is one of main factors of production reduction. therefore, this study was carried out for determination of tomato sensitivity coefficients a...