I'm going to quote from Stanovich (_How to Think Straight about Psychology_, 7th ed., p 167):
"In a variety of clinical domains, when a clinician is given information about a client and asked to predict the client's behavior, and when the same information is quantified and processed by a statistical equation that has been developed based on actuarial relationships that research has uncovered, invariably the equation wins."
I believe that Paul Meehl further demonstrated that when clinicians tried to 'improve' the actuarial predictions they actually made them worse!
So, yes, a clinician can make clinical judgments about an individual tailored to that individual, when he or she does this, over the long haul the clinician is going to err more than be correct. Using the aggregate data means that you must accept some error in particular cases in order to reduce overall error. There is a *lot* of research on this.
The problem with second-guessing the data is that we do not know *how* we should deviate from the actuarial predictions. We might have a clinical "sense," we might rely on our clinical "experience," but those judgments are as fraught with bias as any human judgment. It's only by (somewhat slavishly) adhering to the data that we can be even reasonably sure we know what we're doing.
Otherwise, it seems to me, we might as well forgo the expense and time of going to school.
m
-- Marc Carter
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"No one in this world, so far as I know, has ever lost money by underestimating the intelligence of the great masses of the plain people." -H. L. Mencken
* PAUL K. BRANDON [EMAIL PROTECTED] * * Psychology Dept Minnesota State University * * 23 Armstrong Hall, Mankato, MN 56001 ph 507-389-6217 * * http://www.mnsu.edu/dept/psych/welcome.html *
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