🚀 go-pugleaf

<U53076@uicvm.uic.edu> writes:

>   Let me first apologize for boring you with such a mundane question.   Anyway
>I am in a dispute about levels of measurement and the appropriate statistics to
>use when dealing with data at the ordinal level.  I'd like to compare performan
>ce on a communication task across two different contexts.  In both cases,
>competence is measured on an ordinal scale, for simplicity's sake, 1, 2, 3.  It
>has been my practice in the past to compute a Pearson product-moment correlatio
>n between the two tasks and to use the resulting r as an indication of the
>degree to which performance is consistent across tasks.  I recently was told
>that this was an inappropriate test cause I was only at the ordinal level.  But
>my references (see esp. Glass & Hopkins, 1984; Heermann & Braskamp, 1970) say
>that the whole levels of measurement question has ben blown out of proportion,
>and that the sort of usage I describe is just fine.  What do you think?

I agree that the levels of measurement question has been blown
out of proportion, but you can easily avoid the whole issue in
your case.  A Pearson product-moment correlation computed on
ranks is also known as a Spearman-rho rank-order correlation.  So
just call your statistic a Spearman rho and everyone should be
happy; you'll be happy because you don't have to recalculate
anything.

gary mcclelland
univ of colorado
mcclella@yertle.colorado.edu