Information Technology Reference
In-Depth Information
Chapter 11
How to Check Measures
for Adequacy
IntroductIon
Perhaps the biggest problem when checking measures for adequacy, in addition to overlooking the fact
that model assumptions are invalid, is the need to examine the model for reliability, and also to generalize
a reliable result to an assumption of validity. Without some test of validity, the results could be bogus
because the model does not measure what it is supposed to measure. The question is, just how should
a model be validated?
Reliability is much easier to show. Simply put, similar data should yield similar results. Therefore,
we can compare results across hospitals and patients from one year to another to see if the results by
hospital change from one year to the next, or if they are relatively the same. If the results do not really
change from year to year, the measure is assumed to be reliable. Validity, however, is a much more dif-
ficult concept to demonstrate; so much so, that often validity is ignored in favor of just demonstrating
reliability. As written in Donabedian, (Donabedian, 1980)
The concept of validity is itself made up of many parts; and there is no precise way of saying what be-
longs to it, or what belongs more appropriately under another heading….I would say that the question
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