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Re: st: restricting margins to significant variables only
From
Richard Williams <[email protected]>
To
[email protected]
Subject
Re: st: restricting margins to significant variables only
Date
Fri, 18 Mar 2011 12:23:04 -0500
At 10:34 AM 3/18/2011, Maarten buis wrote:
--- On Fri, 18/3/11, Richard Williams wrote:
> Having said that, you can always have margins fix some
> variable values at 0. That might make good substantive sense
> in some cases (e.g. you want to make predictions for a group
> coded 0) but I don't see why you would want to do so in this
> case. Indeed, it would be silly to fix a variable at 0 when
> 0 is not a possible or likely value for the variable.
The original question was "Is it advisable to get margins to
base its calculations on only those variables which are
significant?" In that case you do not want to set the variable
to zero but its effect, i.e. a form of stepwise selection,
which I told him was a bad idea.
If i understand the original query, what was being proposed is even
worse than stepwise. It sounded like he wanted to leave the
insignificant variables in the model but treat their effects as
though they were zero. Either way, it sounds like a choice between
bad and worse.
-------------------------------------------
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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