Track obtained permission to use this measure in our study, but
we are not allowed to distribute it. To obtain a copy for your use,
here and contact the source listed.
Portions of the Wechsler Intelligence Scale for Children-Revised
(WISC-R) were used in years 1 and 2 for all three cohorts to assess
child intelligence in early elementary school. This measure was
developed by David Wechsler (1974) as a second version of the intelligence
scale originally introduced in 1949. For the Fast Track Project,
a "short form" of this measure was used which included
two of the ten subtests: Block Design (from the Performance module
of the WISC-R) and Vocabulary (from the Verbal Ability module).
The short form score was then converted into an Estimated IQ Score
using methods provided by Sattler (1992).
Scoring tables from the WISC-R manual were used to create separate
age-adjusted scores for the two subtests for year 1. Since test
administration dates were not recorded when this measure was given,
date of administration from the Family Information Form (FIF) was
used as an approximate interview date of this measure as these two
instruments were typically administered on the same day in year
The Block Design Raw Score was positively skewed in the normative
sample and the high-risk sample. The Vocabulary Raw Score, the Block
Design Age-Adjusted Score, the Vocabulary Age-Adjusted Score, and
the Year 1 Estimated IQ Score were all normally distributed for
both the normative and the high-risk samples.
A limitation for using the IQ score for year 1 is the absence of
norms for children under age 6 (Sattler, 1992). Since age-norming
tables for this measure have a lower limit of age 6 years, 0 months
(age 6-0), scores for children under age 6 in the Fast Track Project
were scaled based on the youngest age bracket available (age 6-0
to age 6-3). A substantial proportion of the year one cohort one
sample -- 22% of the normative sample and 22% of the high-risk sample
-- were under the age of 6.0 years, and thus have potentially inappropriately
scaled scores. The result of this in terms of distributions is a
mild floor effect and heavier tail for the year one IQ scores.
Depending on the question being addressed, analysts may use the
estimated IQ scores or the separate subtest, age-adjusted scores.
Keywords: Intelligence Scale, Verbal Ability, Vocabulary, Block
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21 January 2004