The WISC-R was investigated by using measures
of profile (multivariate) reliability in order to determine
its most reliable dimensions and the precision
and similarity of the multivariate structure across
age groups. Due to differences among the 11 age
groups in both subscale reliabilities and true score
covariance matrices, it was concluded that the precision
of measurement differed across age groups.
This finding was further supported by a comparison
of canonical reliability coefficients and composites
computed for each age group. However, exhaustive
analyses of Varimax rotated profile dimensions
indicated that the structure of the WISC-R
subscales is rather stable across age groups, but the
reliability of that structure differs systematically. A
synthesis of the analyses indicated that (1) the
WISC-R allows highly reliable comparisons of profile
levels (Full-Scale IQ) at each age level; that (2)
reasonably reliable comparisons of Verbal-Performance
differences can be made at each age level; but
that (3) for other comparisons, caution should be
exercised because of age group differences and potentially
high unreliability. Two strategies for the
interpretation of WISC-R profiles, which take into
account the above findings, are offered.
Conger, Anthony J, Conger, Judith C, Farrell, Albert D & Ward, David. (1979). What can the WISC-R measure? Applied Psychological Measurement, 3, 421-436. doi:10.1177/014662167900300401
Conger, Anthony J.; Conger, Judith Cohen; Farrell, Albert D.; Ward, David.
What can the WISC-R measure?.
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