On 19 Apr 2000 16:30:07 GMT, [EMAIL PROTECTED] (Wen-Feng
Hsiao) wrote:
> The 5-point scale is obvious ordinal scale, while the bipolar scale can
> be interval scale. However, we usually use analyses such as ANOVA,
> Regression, etc. to analyze the collected 5-point data. Is there any
> reasoning behind it? Please indicate me references, if possible.
If a 5-point scale was created or adapted for a study with any
attention to detail, then it will be pretty close to "equal interval"
by intention, and probably by result.
If a scale has only 5 points, then there will be a whole lot of ties
when you apply the rank-order transformation. If you read your
statistical texts closely, you will see that they raise some doubts
about using ranks when there are ties. Agresti has a good example of
alternative, competing scorings for a few derived categories, in each
of his books on categorical analyses.
I think you have been exposed to the prejudices of a few
Experimentalists in psychology and education, who were
overly-impressed--for a little while, about 30 or 40 years ago--with
the miracles of "nonparametric analyses which don't need any
assumptions!" A 5-point scale happens to be "ordinal" which is a
word that impressed a few people; but it is not well suited to
rank-transforming (the ad-hoc solution for ties is not great).
There were few (no?) credible sources that ever recommended ranking
the 5-point scores, as far as I know--and I have asked about this
before. So, statisticians have not considered the question especially
noteworthy. (And, I am curious, Do recent Experimental Design texts
say anything?)
--
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html
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