translogDeriv {micEcon}

Derivatives of a translog function

Description

Calculate the derivatives of a translog function.

Usage

translogDeriv( xNames, data, coef, coefCov = NULL,
   yName = NULL, dataLogged = FALSE )

Arguments

xNames

a vector of strings containing the names of the independent variables.

data

dataframe containing the data.

coef

vector containing all coefficients.

coefCov

optional covariance matrix of the coefficients.

yName

an optional string containing the name of the dependent variable. If it is NULL, the dependent variable is calculated from the independent variables and the coefficients.

dataLogged

logical. Are the values in data already logged?

Value

a list of class translogDeriv containing following objects:

deriv

data frame containing the derivatives.

variance

data frame containing the variances of the derivatives (not implemented yet).

stdDev

data frame containing the standard deviations of the derivatives (not implemented yet).

Author(s)

Arne Henningsen

See Also

translogEst, translogCalc and translogHessian

Examples

   data( germanFarms )
   # output quantity:
   germanFarms$qOutput <- germanFarms$vOutput / germanFarms$pOutput
   # quantity of variable inputs
   germanFarms$qVarInput <- germanFarms$vVarInput / germanFarms$pVarInput
   # a time trend to account for technical progress:
   germanFarms$time <- c(1:20)

   # estimate a translog production function
   estResult <- translogEst( "qOutput", c( "qLabor", "land", "qVarInput", "time" ),
      germanFarms )

   # compute the marginal products of the inputs (with "fitted" Output)
   margProducts <- translogDeriv( c( "qLabor", "land", "qVarInput", "time" ),
      germanFarms, coef( estResult ), vcov( estResult ) )
   margProducts$deriv

   # compute the marginal products of the inputs (with observed Output)
   margProductsObs <- translogDeriv( c( "qLabor", "land", "qVarInput", "time" ),
      germanFarms, coef( estResult ), vcov( estResult ), "qOutput" )
   margProductsObs$deriv