translogDeriv: Derivatives of a translog function

Description

Calculate the derivatives of a translog function.

Usage

translogDeriv( xNames, data, coef, coefCov = NULL,
   yName = NULL, quadHalf = TRUE, 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.

quadHalf

logical. Multiply the quadratic terms by one half?

dataLogged

logical. Are the values in data already logged?

Value

a list of class translogDeriv containing following objects:
derivdata frame containing the derivatives.
variancedata frame containing the variances of the derivatives (not implemented yet).
stdDevdata frame containing the standard deviations of the derivatives (not implemented yet).

Examples

Run this code

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

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