Forum: help

RE: Inverse Almost Ideal Demand flexibilities [ Reply ] By: Arne Henningsen on 2017-05-28 15:47	[forum:45163]
... and if one or both of you want to implement the inverse AIDS in an R package (e.g. in micEconAids or a new package) -- which is probably much easier than you think -- I could assist you with this. /Arne

RE: Inverse Almost Ideal Demand flexibilities [ Reply ] By: ena Jane on 2017-05-25 15:14	[forum:45160]
Hi, Stefan! These days I am trying to estimate inverse-Aids.But I found there are no relevant packages to use. Then I found your messages here about testing 'Flexibility of Inverse-Aids'. I wonder how you impose the Inverse-Aids in R? Is it ok to share the codes with me? So that I can take a reference. Please contact with quanyinhua0406@gmail.com Thank you so much! Kind Regards --From Jane

RE: Inverse Almost Ideal Demand flexibilities [ Reply ]
By: Arne Henningsen on 2017-04-11 20:39

[forum:45093]

Hi Stefan

I would do the following:

a) create 'shortcuts' for the coefficients, e.g. by:
R> bAlaska <- coef( IAIDSsys13 )[ "<name of regressor>" ]
R> bCod <- coef( IAIDSsys13 )[ "<name of regressor>" ]
R> gAlaskaAlaska <- coef( IAIDSsys13 )[ "<name of regressor>" ]
R> gAlaskaCod <- gCodAlaska <-
R+ coef( IAIDSsys13 )[ "<name of regressor>" ]
R> gCodCod <- coef( IAIDSsys13 )[ "<name of regressor>" ]

b) calculate the price flexibilities, e.g. by:
R> IAIDSforum$flexAlaskaAlaska <- with( IAIDSforum,
R+ -1 + ( gAlaskaAlaska + bAlaska * ( wAlaska - bAlaska * lnQ ) ) /
R+ wAlaska )
R> IAIDSforum$flexAlaskaCod <- with( IAIDSforum,
R+ ( gAlaskaCod + bAlaska * ( wCod - bCod * lnQ ) ) /
R+ wAlaska )
R> IAIDSforum$flexCodAlaska <- with( IAIDSforum,
R+ ( gCodAlaska + bCod * ( wAlaska - bAlaska * lnQ ) ) /
R+ wCod )
R> IAIDSforum$flexCodCod <- with( IAIDSforum,
R+ -1 + ( gCodCod + bCod * ( wCod - bCod * lnQ ) ) /
R+ wCod )

ATTENTION: untested code!!!

Further explanations are given in my lecture notes "Introduction to Econometric Production Analysis with R":
http://leanpub.com/ProdEconR/
These lecture notes focus on econometric production analysis but the procedures are basically the same as those for econometric demand analysis.

/Arne

Inverse Almost Ideal Demand flexibilities [ Reply ]
By: Stefan Stefic on 2017-04-10 12:25

[forum:45089]

I need to calculate flexibilities of the Inverse AIDS model, with estimation and standard error..

IAIDSAlaska=Ralaska~lnQ+lnAlaska+lnHaddock+lnCod
IAIDSHaddock=Rhaddock~lnQ+lnAlaska+lnHaddock+lnCod
IAIDSCod=Rcod~lnQ+lnAlaska+lnHaddock+lnCod

sysIAIDS12=list(IAIDSAlaska,IAIDSHaddock)
IAIDSsys12=systemfit(sysIAIDS12,data=IAIDSforum, method = "SUR")
summary(IAIDSsys12)

sysIAIDS13=list(IAIDSAlaska,IAIDSCod)
IAIDSsys13=systemfit(sysIAIDS13,data=IAIDSforum, method = "SUR")
summary(IAIDSsys13)

I need help for calculating the own and cross price flexibility which formula is
fij= - δij+{γij+βi (wj- βj lnQ)}⁄(wi