Background to my interest in teaching children with autism

The most widely used test in North America [at the time this was written. RR] is the Minnesota Multiphasic Personality Inventory (MMPI). As a whole, this test has a good deal of ‘face’ validity, as the questions it asks are generally the types of questions one might ask in a clinical assessment interview. However, as a whole, it has very little of the other kinds of validity. Actually, this makes it a truly wonderful test. Literally hundreds of research studies have been done, for example, to find ‘scales’ comprised of some of the MMPI items to predict or measure a wide range of variables – uses for the test never dreamed of by its originators. Each scale includes only some of the test’s items, and each scale may be highly valid (or not) even although the test as a whole is not. A highly valid test can be used primarily to measure what it was set up to measure (only).
There are also several different types of ‘reliability’ which are recognized. ‘Retest’ reliability defines the stability of the test over repeated applications with the same people. ‘Split-half’ reliability estimates the extent to which the test is comprised of parts which are internally consistent with each other. ‘Item-scale’ reliability addresses the extent to which the items consistently contribute to the measurement of the same thing. And ‘standard error of the mean’ reliability is concerned with precision or the extent to which the measures consistently create equivalent measures among the same types of people. It would certainly seem that concern with reliability features of a scale would be useful and important. And they are.

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