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Re: st: winzorized mean comparison
On 17 Iúil 2006, at 13:43, Chapman, Ben P wrote:
Dear Stata list,
Winsorising is named after the British Royal Family, whose motto is
'ignore anything odd' (de gustibus, nil, nisi noster').
A colleague in biostatistics has a Stata inquiry that's stumped me.
I know there's a program for winsorizing means, but he is curious
to know if stata has any procedure for comparing two or more
independent groups with trimmed or winsorized means, rather than
conventional means as in a t-test. Apropros of the recent
discussion about FAQs, I have indeed searched and see nothing on
this. Any thoughts much appreciated.
If you want to examine the effect of outlying observations on the
conclusions of a regression, try robust regression (-rreg-), which
downweights observations iteratively rather than giving them all the
snip at once.
However, this is really just a check to see whether the substantive
conclusions of your analysis can be altered when observations with
extreme influence on the model are down-weighted. Your problem of
estimating effect sizes - if you had one - remains.
If you have seriously disturbed data, you could try -ologit- on the
data re-expressed as suitable quantiles (deciles, say).
Royal College of Surgeons in Ireland
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