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Last data update: 2014.03.03

R: Calculate dependent variable of a translog function

translogCalc

R Documentation

Calculate dependent variable of a translog function

Description

Calculate the dependent variable of a translog function.

Usage

translogCalc( xNames, data, coef, shifterNames = 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: if there are `n` exogenous variables in `xNames` and `m` shifter variables in `shifterNames`, the `n+1` alpha coefficients must have names `a_0`, ..., `a_n`, the `n*(n+1)/2` beta coefficients must have names `b_1_1`, ..., `b_1_n`, ..., `b_n_n`, and the `m` delta coefficients must have names `d_1`, ..., `d_m` (only the elements of the upper right triangle of the beta matrix are directly obtained from `coef`; the elements of the lower left triangle are obtained by assuming symmetry of the beta matrix).
`shifterNames`	a vector of strings containing the names of the independent variables that should be included as shifters only (not in quadratic or interaction terms).
`dataLogged`	logical. Are the values in `data` already logged?

Value

A vector containing the endogenous variable. If the inputs are provided as logarithmic values (argument dataLogged is TRUE), the endogenous variable is returned as logarithm; non-logarithmic values are returned otherwise.

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 )

   translogCalc( c( "qLabor", "land", "qVarInput", "time" ), germanFarms,
      coef( estResult ) )
   #equal to estResult$fitted