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Date:         Mon, 31 Jul 2006 13:27:01 +0200
Reply-To:     Spousta Jan <JSpousta@CSAS.CZ>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Spousta Jan <JSpousta@CSAS.CZ>
Subject:      Re: Transforming into normal distro
Comments: To: Marc <marc_feuerstein@yahoo.com>
Content-Type: text/plain; charset="US-ASCII"

Hi Marc,

The best possible try is to use normal scores RANK ... /NORMAL.

GET FILE='C:\Program Files\SPSS\Cars.sav'. NPAR TESTS /K-S(NORMAL)= weight /MISSING ANALYSIS. RANK VARIABLES=weight (A) /NORMAL /PRINT=YES /TIES=MEAN /FRACTION=BLOM . NPAR TESTS /K-S(NORMAL)= Nweight /MISSING ANALYSIS.

But beware: 1) The transformation is generally very much non-linear and hard to generalize 2) In some cases (discrete variables) it is impossible to obtain a normal distribution even with this method.

Usually one rather tries "standard" transformations (log, 1/x, exp, arctg...) to obtain something more Gaussian (even if not perfect Gaussian) or uses non-parametric methods which does not require normality.

Greetings

Jan

-----Original Message----- From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of Marc Sent: Monday, July 31, 2006 1:13 PM To: SPSSX-L@LISTSERV.UGA.EDU Subject: Transforming into normal distro

Hello everybody.

I made the K-S test on the dependent variable and saw that it is not normally distributed (Asymp. Sig. = 0,000).

Is there a data transformation or some magical incantation that exists somewhere to transform this data into a normally distributed set ?

Bye,


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