FAQ/ResidualsNonNormality - CBU statistics Wiki

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WHat wOrd is made by the captiaL lettErs?

location: FAQ / ResidualsNonNormality

Residuals and Non-normality

This page will give some tips on aspects of looking at residuals in order to assess non-normality. In particular it will stress how

  • in repeated measures data, the thing that matters is the distributions of differences between pairs of measures (or more general contrasts in the repeated measures).
  • in grouped data, it is the residuals adjusted for group means that matter

Consider this very small example:

X1

X2

1

2

2

1

3

2

1001

1002

The distributions of the variables are very skewed. The distribution of the differences (for a repeated measures t-test) are at least symmetrical, if not normal. [Last updated on 21 September, 2010]


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