lrtest.aidsEst {micEconAids}

Likelihood Ratio test for Almost Ideal Demand Systems

Description

Testing hypothesis in Almost Ideal Demand Systems by a Likelihood Ratio test.

Usage

   ## S3 method for class 'aidsEst'
lrtest( object, ... )

Arguments

object

a fitted model object of class aidsEst.

...

further fitted model objects of class aidsEst.

Details

lrtest.aidsEst consecutively compares the fitted model object object with the models passed in ....

Value

An object of class anova, which contains the log-likelihood value, degrees of freedom, the difference in degrees of freedom, likelihood ratio Chi-squared statistic and corresponding p value. See documentation of lrtest in package "lmtest".

Author(s)

Arne Henningsen

See Also

aidsEst, lrtest (package "lmtest"), logLik.aidsEst

Examples

   # Using data published in Blanciforti, Green & King (1986)
   data( Blanciforti86 )
   # Data on food consumption are available only for the first 32 years
   Blanciforti86 <- Blanciforti86[ 1:32, ]

   # names of prices and expenditure shares
   priceNames <- c( "pFood1", "pFood2", "pFood3", "pFood4" )
   shareNames <- c( "wFood1", "wFood2", "wFood3", "wFood4" )

   # estimation with symmetry and homogeneity imposed
   estResult <- aidsEst( c( "pFood1", "pFood2", "pFood3", "pFood4" ),
      c( "wFood1", "wFood2", "wFood3", "wFood4" ), "xFood",
      data = Blanciforti86 )

   # estimation with only homogeneity imposed
   estResultHom <- aidsEst( c( "pFood1", "pFood2", "pFood3", "pFood4" ),
      c( "wFood1", "wFood2", "wFood3", "wFood4" ), "xFood",
      data = Blanciforti86, sym = FALSE )

   # unrestricted estimation
   estResultUnr <- aidsEst( c( "pFood1", "pFood2", "pFood3", "pFood4" ),
      c( "wFood1", "wFood2", "wFood3", "wFood4" ), "xFood",
      data = Blanciforti86, sym = FALSE, hom = FALSE )

   # LR tests
   lrtest( estResult, estResultHom, estResultUnr, estResult )

   ## Estimation with a demand shifter: linear trend
   Blanciforti86$trend <- c( 0:( nrow( Blanciforti86 ) - 1 ) )
   estResultTrend <- aidsEst( priceNames, shareNames, "xFood",
      data = Blanciforti86, shifterNames = "trend" )

   # LR tests
   lrtest( estResult, estResultTrend )