Thanks Rich. I went with the Pearson r—as you said it’s plain. -Steve
From: SPSSX(r) Discussion [mailto:[hidden email]]
On Behalf Of Rich Ulrich
Sent: Wednesday, April 23, 2014 12:27 PM
To: [hidden email]
Subject: Re: Correlation between ordinal data
I'm pretty sure that I would stick with the plain, old Pearson r.
Spearman is much better suited to continuous data: Is there
really any improvement in anything by transforming (1,2,3) into
the "average rank" observed with massive numbers of ties? Of
course, if you ask for a Monte Carlo evaluation, you do get an
"exact" test. Otherwise, the tests on Spearman are only as good
as the adjustment-in-error made for ties (which is not always so
good).
My impression of the tetrachoric and polychoric correlations is
that they have a role where theorists are paying close attention to
using r as a precise measure of the "underlying relationships". The
price of this gain is that you don't have any decent tests... and you
probably mislead your readership, who fail to note that these numbers
are inflated, compared to the r's that they are familiar with for similar
situations.
--
Rich Ulrich
Date: Wed, 23 Apr 2014 10:10:32 -0500
From: [hidden email]
Subject: Re: Correlation between ordinal data
To: [hidden email]
Maybe you can find useful the polychoric correlation:
Regards!!
2014-04-23 10:02 GMT-05:00 Salbod <[hidden email]>:
I have two columns of data made up of 10 rows, representing families. The
data in each row is the choice (Frequently (3), Moderately (2), and Rarely
(1)) made by a family member and professional about another individual. I
am interested if there is a correlation between the two: family members and
professionals.
Does a Spearman rho provide me with this answer or is there a better test?
TIA, Stephen Salbod, Pace University, NYC
| Free forum by Nabble | Edit this page |