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Re: st:. : [problem with outliers in regression]

From   Nazaria Solferino <>
Subject   Re: st:. : [problem with outliers in regression]
Date   Wed, 7 Aug 2002 18:36:06 +0200 (CEST)

Thank you for your help.
Could you give me some suggestions about

> Hello! I'm a new Stata user and I'm not very good at
> using it yet. I hope some one can help with my
> problem. I've a large dataset, with some outliers,
> I'd like to manage variables, that I have, only in a
> restricted range(without dropping observations) I've
> thought I could give a zero value to all veriables
> outside a certain range so I mean I should generate
> newvar=oldvar then replace newvar=0 if outside the
> range. First, is this a sattistical correct

(Please use informative titles on Statalist messages.)

No. Stata will take the new values of 0 just as
as the old outlying values. 

One way to exclude outliers is by an -if- condition: 

regress y x1 x2 x3 if y < 10000 

Naturally, there are other approaches to your problem 

1. a robust technique. I've found -qreg- very good. 

2. transformation. 

3. -glm- with a nonlinear link (e.g. log). 

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