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Re: st: Why does one command "lose" observations compared to another command?


From   Richard Williams <Richard.A.Williams.5@ND.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Why does one command "lose" observations compared to another command?
Date   Sun, 22 Jan 2006 15:32:50 -0500

At 03:02 PM 1/22/2006, Richard Williams wrote:
Does mecwt4 include weights of zero? I am guessing that may be why. svy still counts cases with 0 weights, but mean with the weight parameter does not.
To follow up on my own post - the Stata 9 Data Manual says on p. 10, pt. #6 "svy commands handle zero sampling weights properly. Standard commands ignore any observations with a weight of zero." It then explains how postsampling adjustment procedures can legitimately lead to weights of zero and how estimates of standard errors can sometimes be affected if zero weights are not handled properly.

Assuming you do have zero weights, you may want to verify that they are legit and shouldn't really be missing instead.


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