translogDeriv function

Derivatives of a translog function

Calculate the derivatives of a translog function.

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?

Returns

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).

See Also

translogEst, translogCalc and translogHessian

Author(s)

Arne Henningsen

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