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Re: st: margins using weights in calculation?
From
Richard Williams <[email protected]>
To
[email protected], [email protected]
Subject
Re: st: margins using weights in calculation?
Date
Sat, 11 May 2013 10:31:15 -0500
I am curious how your number of cases goes down when using pweights.
But in any event the help for margins says "By default, margins uses
the weights specified on the estimator to average responses and to
compute summary statistics. If weights are specified on the margins
command, they override previously specified weights." So, I think
margins is doing it fine, and there is no need for you to repeat the
weight specification on the margins command.
At 02:12 PM 5/10/2013, Brent Gibbons wrote:
When i run a weighted OLS regression (using either iweight or
pweight) with about 13,000 cases, I get a reported number of
observations of about 7,701 (which is what it should be given the
values of the weights. But when I then run a margins command to
compute dydx(*) on these data, with the same weight specified, I get
the original unweighted number of cases (about 13,000) as the
reported # of observations. Does this mean that when "margins" is
averaging marginal effects across all cases, it is disregarding the
weights and taking the simple unweighted average (i.e., giving each
case a weight = 1)?
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-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME: (574)289-5227
EMAIL: [email protected]
WWW: http://www.nd.edu/~rwilliam
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