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From | SAM MCCAW <sam2stata@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Demeaning TFP |
Date | Wed, 10 Oct 2012 17:53:52 -0400 |
Dear All, I am trying to assess productivity spillovers from foreign to domestic firms and am using levpet as my productivity estimation technique. After I run levpet (both on pooled sample and then industry by industry) I get some gigantic values for lnTFP. My sample for running levpet includes both domestic and foreign firms, i.e. I am not running levpet for domestic firms only. The summary stats for lnTFP are as follows: Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- lnTFP_pooled | 21923 -1247.003 106482.5 -1.43e+07 17.18935 lnTFP_industry | 18710 -5587274 3.56e+08 -4.57e+10 24.17001 Now I would like to demean TFP but since I have so many really high negative values, would demeaning lnTFP by country and industry just make it worse? Also, I am afraid to restrict the sample to a certain level of lnTFP, for example as far as - 100. Preferably I would just restrict the sample to exclude outliers but I have about 3000 firms which have lnTFP less than -50 in a total sample of 21923. Also, if I go ahead and use these lnTFP values in my regression, by elasticity magnitudes turn up to be 4 digits long. Yikes. I have tried data transformations and so on but am at a loss. Any thoughts would be greatly appreciated. Thanks. SAM * * 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/