SPSSX Discussion - Re: Winsorizing in meta-analysis

Re: Winsorizing in meta-analysis

Posted by Bruce Weaver on May 01, 2011; 12:37am
URL: http://spssx-discussion.165.s1.nabble.com/Winsorizing-in-meta-analysis-tp4361802p4362030.html

Hi Art. Several years ago, I worked for a group that did a lot of meta-analysis, and Winsorizing was never part of their procedure. But as I say, that was several years ago. However, I've just searched the Cochrane Handbook (http://www.cochrane-handbook.org/) for "Winsorize" (and "Winsorise"), and found no mention of it there either.

Just to be clear, is your colleague suggesting Winsorization of the point estimates from the various studies before computation of the pooled estimate? Are they computing a fixed or random effects estimate? Do they have a priori hypotheses about possible heterogeneity of the point estimates?

HTH.

Cheers,
Bruce

Art Kendall wrote

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

I am not near my books right now, so I would like to
get feedback from the list.

A colleague was saying that she took a course a few weeks ago, and
the prof said that winsorizing usually should be done in
meta-analysis. I found this surprising but she was adamant.

In general, over analyses in general I have found that a
subjective 80% of anomalous values are data entry errors. I have
grudgingly trimmed or winsorized only when the value of a
variable is substantively implausible?

What is your experience?

Is routinely winsorizing in meta-analysis what you teach?

If you do winsorize in meta-analysis, how often do you do it? How
do you decide when to do it?

Is this the current practice?

Art Kendall
Social Research Consultants

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Bruce Weaver
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"When all else fails, RTFM."

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