The bias in regression-based indices of premorbid IQ.
Psychol Assess
; 13(3): 356-68, 2001 Sep.
Article
in En
| MEDLINE
| ID: mdl-11556272
ABSTRACT
Formulas for premorbid intelligence estimates are typically derived by linear regression and are therefore biased in individual cases because of regression to the mean. It is shown that it is inappropriate to compare such IQ estimates with current IQ scores to determine whether a decline from premorbid levels has occurred. This widespread practice grossly overestimates the probability of an IQ decline in the below-average range and grossly underestimates it in the above-average range, with serious implications for clinical practice. The authors present a formula for computing unbiased estimates of IQ decline as well as a test of the null hypothesis of no decline. Corresponding tables for several combinations of test indices and estimation methods are included for practical reference.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Brain Injuries
/
Disability Evaluation
/
Intelligence
/
Intelligence Tests
Type of study:
Diagnostic_studies
/
Guideline
/
Prognostic_studies
Limits:
Adult
/
Humans
/
Male
Language:
En
Journal:
Psychol Assess
Journal subject:
PSICOLOGIA
Year:
2001
Document type:
Article
Affiliation country:
Canadá