Re: [R] negatively skewed data; reflecting

From: Michael Kubovy <kubovy_at_virginia.edu>
Date: Wed 23 Aug 2006 - 23:11:22 EST

On Aug 23, 2006, at 8:08 AM, z.dalton@lancaster.ac.uk wrote:

> I have constructed histograms of various variables in my dataset.
> Some of them are negatively skewed, and hence need data
> transformations applied. I know that you first need to reflect the
> negatively skewed data and then apply another transformation such
> as log, square root etc to bring it towards normailty. How is it
> that I reflect data in R?
>
>> hist(Lsoc) #how do I reflect Lsoc in R?

To reflect the vector Lsoc, assuming the numbers are positive, and keep them positive in order to take (e.g.) logs, log(-Lsoc + max(Lsoc) + 1).

But if you do a Google search on 'ladder powers negative skew' you'll find another answer. The idea of the ladder of powers is due to J W Tukey.



Professor Michael Kubovy
University of Virginia
Department of Psychology
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