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RE: st: Looping Enquiry

From   Nick Cox <>
To   "''" <>
Subject   RE: st: Looping Enquiry
Date   Thu, 29 Sep 2011 15:21:06 +0100

This is normally a good idea, but in this case the variable concerned is often negative, which to me implies that other methods have greater appeal. 


Valerie Orozco

The first idea that comes in my mind is to transform the problem.
If you think in a sum rather than in a product it will be easier to program it.
Indeed,  since the logarithm of a product is the sum of the logarithms, you can use it to program you formula easier in Stata.

score	transform to log	generate a cumulative sum	transform to exponential to have what you want 
x1	lnx1	                                         lnx1	                                                  x1
x2	lnx2	                                         lnx1+lnx2	                                                     x1x2
x3	lnx3	                                                  lnx1+lnx2+lnx3	              x1x2x3

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