Translog Ray Frontiers

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Description

This is a convenient interface for estimating translog stochastic ray frontier models using frontier.

Usage

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frontierTranslogRay( yNames, xNames, shifterNames = NULL,
   zNames = NULL, data, ... )

Arguments

yNames

a vector of two or more character strings containing the names of the output variables.

xNames

a vector of strings containing the names of the input variables that should be included as linear, quadratic, and interaction terms.

shifterNames

a vector of strings containing the names of the explanatory variables that should be included as shifters only (not in quadratic or interaction terms).

zNames

a vector of strings containing the names of the Z variables (variables explaining the efficiency level).

data

a (panel) data frame that contains the data (see documentation of frontier) NOTE: the variables defined by arguments yNames and xNames must be in natural units; the variables defined by argument xNames are logarithmized internally; the variables defined by arguments shifterNames and zNames are NOT logarithmized internally and hence must be specified as they should be used in the model.

...

further arguments passed to frontierQuad and possibly further to frontier.

Value

frontierTranslogRay returns a list of class frontierTranslogRay (as well as frontierQuad and frontier) containing almost the same elements as returned by frontier. Additionally, it includes following objects:

distance

the “distance” from the origin (zero) to the point of the dependent variables.

theta_i

the “direction” from the origin (zero) to the point of the dependent variables (with i = 1, ..., N-1 and N is the number of outputs).

Author(s)

Arne Henningsen and Geraldine Henningsen

References

Löthgren, M. (1997) Generalized stochastic frontier production models, Economics Letters, 57, 255-259.

Löthgren, M. (1997) A Multiple Output Stochastic Ray Frontier Production Model, Working Paper Series in Economics and Finance, No. 158, Stockholm School of Economics.

Löthgren, M. (2000) Specification and estimation of stochastic multiple-output production and technical inefficiency Applied Economics, 32, 1533-1540.

See Also

frontier, frontierQuad.

Examples

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## preparing data
data( germanFarms )
# quantity of crop outputs
germanFarms$qCrop <- germanFarms$vCrop / germanFarms$pOutput
# quantity of animal outputs
germanFarms$qAnimal <- germanFarms$vAnimal / germanFarms$pOutput
# quantity of variable inputs
germanFarms$qVarInput <- germanFarms$vVarInput / germanFarms$pVarInput

# estimate a translog ray production function
estResultRay <- frontierTranslogRay( yNames = c( "qCrop", "qAnimal" ),
   xNames = c( "qLabor", "land", "qVarInput" ),
   data = germanFarms )
summary( estResultRay )