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From | natasha agarwal <agarwana2@googlemail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Levpet and Time Dummies. |
Date | Sun, 24 Mar 2013 11:02:20 +0530 |
Dear All, Many thanks for providing kind assistance. I had a further query of this note. I estimate the production function using "levpet" for each industry and then I lump all the industries together and estimate one production function for all. However, I get different results for the predicted TFP when I look for each industry. Can anyone please tell me why is this the case ? Please note that levpet is a user written programme available as a stata module Stata Journal article of the same can be accessed at http://www.stata-journal.com/sjpdf.html?articlenum=st0060. The same can be downloaded as ssc install levpet Best, Natasha On Wed, Mar 20, 2013 at 10:18 PM, Brian P. Poi <bpoi@stata.com> wrote: > On 03/20/2013 10:34 AM, natasha agarwal wrote: > >> Dear All, >> >> Please accept my apologies for the previous post. >> >> I was attempting to calculate the TFP for a sample of firms for the >> period 2001 to 2005 using the levpet command, and wanted to know if >> one can use time dummies in the free variable list ? >> >> Please note that levpet is a user written programme available as a >> stata module by levinsohn and petrin in their co-authored paper in >> 2003. Stata Journal article of the >> same can be accessed at >> http://www.stata-journal.com/sjpdf.html?articlenum=st0060. The same >> can be downloaded as ssc install levpet >> >> Your help will be highly appreciated. >> >> Many thanks, >> Natasha > > > Natasha, > > Rather than including time dummies in the model itself, what I would > recommend is to fit your production function using -levpet- (without the > time dummies) and obtain the estimates of productivity. Then you can use > graphs, descriptive statistics, etc., to see how the productivity evolves > over time. I suspect that if you include time dummies before obtaining the > predicted productivity, you will have "swept under the rug" the interesting > productivity dynamics these estimators are designed to help explore. > > > -- Brian Poi > -- bpoi@stata.com > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/