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From | "Pavlos C. Symeou" <p.symeou@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Index |
Date | Wed, 11 Jan 2012 17:16:52 +0200 |
Dear Statalisters,Happy new year to all. I'd like to ask for your assistance regarding the following:
I have a number of companies for a number of years and each company sells its products in a number of markets in a year. For each market, I have the value of its sales (a proportion relative to the overall sales for the company in a year). I am interested in calculating an index for each company-year as following:
1) for each company-year I must compare each market with each other. If the two markets are the same I take their product and multiply it by 1. If the two markets are not the same, I take their product and multiply them by 2. The index should be the sum of all products.
From the example data below, the Index for Firm 1 in Year 1993 should be:
(0.4 * 0.2 * 1) + (0.4 * 0.4 * 2) + (0.2 * 0.4 * 2) = 0.56 DATA Firm Year Market Market_sales Index 1 1990 1 1 1 1991 1 1 1 1992 2 .3 1 1992 2 .1 1 1992 3 .15 1 1992 2 .15 1 1992 3 .15 1 1992 4 .15 1 1993 4 .40 1 1993 4 .20 1 1993 5 .40 2 1990 1 1 2 1991 1 1 2 1992 2 .3 2 1992 2 .1 2 1992 3 .15 2 1992 2 .15 2 1992 3 .15 2 1992 4 .15 2 1993 4 .40 2 1993 4 .20 2 1993 5 .40 Thanks, Pavlos * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/