Re: Wilcoxon/ t-test, z-standardization

Posted by Kornbrot, Diana on Aug 25, 2012; 7:52am
URL: http://spssx-discussion.165.s1.nabble.com/Wilcoxon-t-test-z-standardization-tp5714842p5714862.html

Ordinal regression is analysis of choice for ordinal level data, this included ALL Likert type single items
To be found under regression, ordinal. Note although under regression one can insert categorical predictors
Also goes under name PLUM – its a peach
Best
Diana


On 24/08/2012 18:16, "Rich Ulrich" <rich-ulrich@...> wrote:

Start over.

a) Since the original Likert scaling uses categories of Agree/ Don't Agree,
I think you should not use that name.  You might say something like
"a Likert-type scaling" if your measure of Time (say) was from "too little"
to "too much".  But that would place "most benefit" - I presume - in the
middle.  

What you have, it seems, is a 4 (and 5) point scale from "xxx" to "yy".
If you have a number of items, they make up a summative scale of parallel
items.

b) You should not apply a paired t-test to these measures, Time and
Benefit, which *seem*  so naturally incommensurable.  A z-transformation
has no chance of equalizing anything.  If your anchor points/ labels  were
carefully chosen, you might have been able to chose some apparent
equivalence between certain levels.  But apparently, that is not the case.

Look at your cross-tabulation.  What can you say about the extreme
corners?  How many are "extremely good" versus "extremely bad"?
You might argue that there are more of one than the other, applying
McNemars test to the two numbers (basically, the sign test).

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