ALSPAC – Age 8.5 – Wechsler Intelligence Scale for Children (WISC-III)

The Avon Longitudinal Study of Parents and Children (ALSPAC) assessed their cohort members (CMs) during the study’s age 8.5 sweep (Focus@8) using the Wechsler Intelligence Scale for Children (WISC-III).

Details on this measure and the data collected from the CMs are outlined in the table below.

Years of data collection:	1999-2001
Domain:	Verbal and non-verbal ability
Measures:	General cognitive ability
	Verbal ability
	Non-verbal/performance ability
CHC:	G (General ability)
CLOSER Source:	Explore this sweep in CLOSER Discovery: ALSPAC Childhood (5 years to 12 years 11 months) (opens in a new tab)
Administration method:	Trained interviewer; clinical setting
Procedure:	The WISC-III is a measure of cognitive functioning designed for children aged 6-17 years. It is comprised of two scales, verbal and performance (non-verbal), and each of these scales contains 5 subtests. The verbal subtests are: i) vocabulary, ii) similarities, iii) arithmetic, iv) information, v) comprehension. The performance subtests are: i) object assembly, ii) coding, iii) block design, iv) picture arrangement, v) picture completion. Each subtest is described individually in the sections below.
	A short-form measure of the WISC was administered to reduce burden/fatigue on the children (with the exception of the coding test which was administered in full). Scores from this short-form version can be transformed to approximate scores on the full version as follows; multiplying by 2 scores for picture completion, information, arithmetic, vocabulary, comprehension and picture arrangement; multiplying by 5/3 for similarities; and multiplying by 3/2 for object assembly and block design.
	The WISC-III provides standard scores (M = 100, SD = 15), on verbal IQ, performance IQ and fullscale IQ. Scores on the individual subtests were standardised (M = 10, SD = 3). Raw scores were converted into scale scores using tables provided in the WISC-III manual. If fewer than 3 subtests were completed by the child, verbal, performance and fullscale IQ were not computed for that child. If 4 out of 5 subscales were completed on the verbal/performance scales, the mean of the 4 scales was substituted in for the missing 5th. This prorating strategy is a standard practice when using WISC-III.
Link to questionnaire:	http://www.bristol.ac.uk/alspac/researchers/our-data/clinical-measures/ (opens in new tab)
Scoring:	Standardised score (M = 100, SD = 15)
Item-level variable(s):	Not readily available
Total score/derived variable(s):	f8ws020 – f8ws155 Explore these variables in CLOSER Discovery: ALSPAC Focus at 7 Clinic Dataset (opens in a new tab)
Descriptives:	Total IQ	Verbal IQ	Performance IQ
	N = 7,348	N = 7,379	N = 7,371
	Range = 45 – 151	Range = 46 – 155	Range = 46 – 151
	Mean = 103.97	Mean = 106.95	Mean = 99.46
	SD = 16.53	SD = 16.79	SD = 17.12
	(click image to enlarge)	(click image to enlarge)	(click link to enlarge)
Age of participants (months):	Mean = 103.82 months, SD = 3.92, Range = 89 – 127
Other sweep and/or cohort:	None
Source:	Wechsler, D. (1991). WISC-III: Wechsler intelligence scale for children: Manual. Psychological Corporation.
Technical resources:	Kaufman, A. S., & Lichtenberger, E. O. (2000). Essentials of WISC-III and WPPSI-R assessment. John Wiley & Sons Inc.
Example articles:	Northstone, K., Joinson, C., Emmett, P., Ness, A., & Paus, T. (2012). Are dietary patterns in childhood associated with IQ at 8 years of age? A population-based cohort study. Journal of Epidemiology and Community Health, 66(7), 624-628.
	Bornstein, M. H., Hahn, C. S., & Wolke, D. (2013). Systems and cascades in cognitive development and academic achievement. Child Development, 84(1), 154-162.

For the named items in the table above, links are provided to their corresponding content on CLOSER Discovery. Where a variable range is provided, full variable lists can be accessed through the ‘Variable Groups’ tab on the linked Discovery page.