LISTSERV at the University of Georgia
Menubar Imagemap
Home Browse Manage Request Manuals Register
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (September 2005)Back to main SPSSX-L pageJoin or leave SPSSX-L (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:         Sun, 25 Sep 2005 13:03:01 +0200
Reply-To:     Marta García-Granero
              <biostatistics@terra.es>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Marta García-Granero
              <biostatistics@terra.es>
Organization: Asesoría Bioestadística
Subject:      Re: MANCOVA data transformation
In-Reply-To:  <20050923.231812.548.4.babyblue325@juno.com>
Content-Type: text/plain; charset=ISO-8859-15

Hi Jordan,

JH> I am analyzing the data for my dissertation and I've got a Box's M on one JH> of my DV's (I can tell which one, due to outliers on each end). Since the JH> DV is a ratio, arcsine has been suggested to me as a transformation.

Are you talking about a percentage or just the ratio of two quantitative variables?

Arcsin transformation is suitable for percentages (or fractions, but not any ratio) that are likely to follow a binomial law (instead of the normal law), provided that the denominator is a constant. If lack of HOV is caused simply by some outliers, but not because your data are binomially distributed, then it is not a good idea at all to arcsin transform them.

JH> do you think would be best? And can I only transform one of the two DV's, JH> or do I have to do both? Also, once I transform the data, what other JH> things do I need to keep in mind when looking at other parts of the data? JH> Meaning, the means of the DV etc. These have to be converted back, yes?

Some transformations can be undone, that's why I consider a bit dangerous to use then without a solid reason.

Regards, Marta mailto:biostatistics@terra.es


Back to: Top of message | Previous page | Main SPSSX-L page