micEcon (version 0.2-4)

aidsEla: Elasticities of the AIDS model

Description

Calculates the demand elasticities of an AIDS model.

Usage

aidsEla( coef, W, P = NULL, formula = "AIDS",
      qNames = NULL, pNames = NULL, coefVcov = NULL, df = NULL )

Arguments

coef

a list containing the coefficients alpha, beta and gamma.

W

a vector of the shares at which the elasticities should be calculated.

P

a vector of the prices at which the elasticities should be calculated (only needed if formula 'AIDS' is used).

formula

the elsticity formula to be used (see details).

qNames

an optional vector of strings containing the names of the quantities to label elasticities.

pNames

an optional vector of strings containing the names of the prices to label elasticities.

coefVcov

variance covariance matrix of the coefficients (optional).

df

degrees of freedom to calculate P-values of the elasticities (optional).

Value

• a list of class aidsEla containing following elements:
• formula
  the elasticity formula used to calculate these elasticities.
• exp
  vector of expenditure elasticities.
• hicks
  matrix of Hicksian (compensated) price elasticities.
• marshall
  matrix of Marshallian (uncompensated) price elasticities.
• allVcov
  variance covariance matrix of all elasticities.
• expVcov
  variance covariance matrix of the expenditure elasticities.
• hicksVcov
  variance covariance matrix of the Hicksian (compensated) price elasticities.
• marshallVcov
  variance covariance matrix of the Marshallian (uncompensated) price elasticities.
• expStEr
  standard errors of the expenditure elasticities.
• hicksStEr
  standard errors of the Hicksian (compensated) price elasticities.
• marshallStEr
  standard errors of the Marshallian (uncompensated) price elasticities.
• expTval
  t-values of the expenditure elasticities.
• hicksTval
  t-values of the Hicksian (compensated) price elasticities.
• marshallTval
  t-values of the Marshallian (uncompensated) price elasticities.
• expPval
  P-values of the expenditure elasticities.
• hicksPval
  P-values of the Hicksian (compensated) price elasticities.
• marshallPval
  P-values of the Marshallian (uncompensated) price elasticities.

Details

At the moment only the elasticity formulas of the orginal AIDS ('AIDS'), the formula of Chalfant (1987) ('Ch') and the formula of Eales and Unnevehr (1988) ('EU') are implemented. The variance covariance matrices of the elasticities are calculated using the formula of Klein (1953, p. 258) (also known as the delta method). At the moment this is implemented only for the elasticity formulas of the orginal AIDS.

References

Chalfant, J.A. (1987) A Globally Flexible, Almost Ideal Demand System. Journal of Business and Economic Statistics, 5, p. 233-242.

Deaton, A.S. and J. Muellbauer (1980) An Almost Ideal Demand System. American Economic Review, 70, p. 312-326.

Eales J.S. and L.J. Unnevehr (1988) Demand for beef and chicken products: separability and structural change. American Journal of Agricultural Economics, 70, p. 521-532. Klein L.R. (1953) A Textbook of Econometrics. Row, Petersen and Co., New York.

See Also

aidsEst

Examples

data( Blanciforti86 )
   # Data on food consumption are available only for the first 32 years
   Blanciforti86 <- Blanciforti86[ 1:32, ]

   estResult <- aidsEst( c( "pFood1", "pFood2", "pFood3", "pFood4" ),
      c( "wFood1", "wFood2", "wFood3", "wFood4" ), "xFood",
      data = Blanciforti86, method = "LA:L" )
   wMeans <- colMeans( Blanciforti86[ , c( "wFood1", "wFood2",
      "wFood3", "wFood4" ) ] )
   aidsEla( estResult$coef, wMeans, formula = "Ch" )