logLik.frontier {frontier}R Documentation

Extract Log-Likelihood Value

Description

Extract the log-likelihood value(s) from stochastic frontier models returned by frontier.

Usage

## S3 method for class 'frontier':
logLik( object, which = "mle", newParam = NULL, ... )

Arguments

object an object of class frontier (returned by the function frontier).
which character string. Which log-likelihood value should be returned? 'ols' for the log-likelihood value of the parameters estimated by OLS, 'grid' for the log-likelihood value of the parameters obtained by the grid search (only if no starting values were provided), 'start' for the log-likelihood value of the starting values of the parameters specified by the user (only if starting values were provided), or 'mle' for the log-likelihood values of the parameters estimated by Maximum Likelihood.
newParam optional vector of parameters. If this argument is provided by the user, the log-likelihood value of the model object is calculated with these (new) parameters.
... currently unused.

Value

logLik.frontier returns a scalar.

Author(s)

Arne Henningsen

See Also

frontier.

Examples

   # example included in FRONTIER 4.1
   data( front41Data )
   front41Data$logOutput  <- log( front41Data$output )
   front41Data$logCapital <- log( front41Data$capital )
   front41Data$logLabour  <- log( front41Data$labour )

   # SFA estimation with starting values obtained from a grid search
   sfa <- frontier( yName = "logOutput",
      xNames = c( "logCapital", "logLabour" ), data = front41Data )
   logLik( sfa, which = "ols" )
   logLik( sfa, which = "grid" )
   logLik( sfa )

   # SFA estimation with starting values provided by the user
   sfa2 <- frontier( yName = "logOutput",
      xNames = c( "logCapital", "logLabour" ), data = front41Data,
      startVal = 0.9 * coef( sfa ) )
   logLik( sfa2, which = "ols" )
   logLik( sfa2, which = "start" )
   logLik( sfa2 )

   # evaluate log likelihood function for a user-provided parameter vector
   logLik( sfa, newParam = 0.9 * coef( sfa ) )
      # equal to  logLik( sfa2, which = "start" )

   # log likelihood function for different values of gamma
   plot( t( sapply( seq( 0.05, 0.95, 0.05 ), function(x) c( x,
      logLik( sfa, newParam = c( coef( sfa )[1:4], x ) ) ) ) ) )

[Package frontier version 0.991-0 Index]