Hi Teresa,
I recommend that you look at Sensitivity and Specificity (or LRs) of
each test rather than correlation coefficient. Even if the two tests
are highly correlated it doesn't mean that they will identify the same
people, or even be equally good at defining sick from well (normal from
abnormal persons). In fact, correlation would work well for surrogate
markers, that have nothing to do with the disease process being
measured.
Hope this helps,
Best wishes,
Dan
****************************************************************************
Dan Mayer, MD
Professor of Emergency Medicine
Albany Medical College
47 New Scotland Ave.
Albany, NY, 12208
Ph; 518-262-6180
FAX; 518-262-5029
E-mail; [log in to unmask]
****************************************************************************
>>> "Benson, Teresa" <[log in to unmask]> 3/10/2008 11:15 AM
>>>
If you are using correlation coefficients to decide whether one
clinical
test can be substituted for another, particularly with non-dichotomous
values (e.g., blood glucose), is there a certain minimum value you
look
for? (Assuming, of course, the new test is cheaper or easier.) Or do
you always just look at things like sensitivity/specificity and
predictive value, and disregard the correlation coefficients? The old
User's Guide to the Medical Literature recommends a correlation
coefficient of at least .8, but I'd like to know what others think
about
this.
Teresa Benson, M.A., Licensed Psychologist
Senior Clinical Content Specialist, InterQual Products
McKesson Health Solutions
18211 Yorkshire Avenue
Prior Lake, MN 55372
952-226-4033
[log in to unmask] <mailto:[log in to unmask]>
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