DOI: 10.60641/nw23-yy58
title: Wechsler Intelligence Scale for Children (WISC)

description: The Netherlands Twin Register (NTR) consists of individuals who have agreed to participate in twin-family studies and was established and is managed by the Department of Biological Psychology, VU University Amsterdam (see: https://tweelingenregister.vu.nl/). The NTR was established in 1987 and has enrolled around 120.000 twins and a roughly equal number of their relatives. The majority of twin families have participated one or more times in survey studies on a host of epidemiological variables including social demography, personality, lifestyle, somatic and mental health, and subsamples took part in biomaterial collection (e.g. DNA) and dedicated projects for e.g. neuropsychological, biomarker, and behavioral traits. The recruitment into the NTR is fully inclusive without any restrictions on enrolment. The NTR is committed to actively seek the commitment of its participants to science and their continued involvement in NTR research by maintaining a website, electronic newsletters, and the MijnNTR portal that provides personalized feedback to participants. The NTR resources, e.g. the longitudinal phenotyping, the extended pedigree structures, and the multi-generation genotyping allow for future twin-family research that will contribute to gene discovery, causality modelling, and studies of genetic and cultural inheritance of behavioral traits and mental and physical health. In the CID data catalogue, only the NTR projects for children and adolescents (<18 years of age) have been included. This is refered to as the Young Netherlands Twin Register (YNTR). 
description: The Wechsler Intelligence Scale for Children (WISC) is an IQ test for children of 6-17 years of age to determine general intelligence. It generates a full scale IQ (formerly known as an intelligence quotient or IQ score) that represents a child's general intellectual ability. The most common primary index scores are the Verbal Comprehension Index, the Visual Spatial Index, the Fluid Reasoning Index, the Working Memory Index, and the Processing Speed Index. These indices represent a child's abilities in discrete cognitive domains. Five ancillary composite scores can be derived from various combinations of primary or primary and secondary subtests. Different versions may contain different sub tests.
description: In NTR project YC_BS1, participants were tested by a series of subtests from the WISC-III: picture completion, information, coding, similarities, picture arrangement, arithmetic, block design, vocabulary, object assembly, comprehension, symbol search, and digit span. In NTR project YC_BS2, following subtests from the WISC-III were included: similarities, arithmetic, vocabulary, digit span, picture completion, and block design. For the calculation of the raw scores on full IQ scale and on the verbal, and performance scale a correction was used to account for the number of excluded subtests. Raw scores were standardized according the age of the child at the time of testing, based on a population sample of same-aged subjects in the Netherlands. In NTR project YE_ATTEF2, the following subtests from the Dutch Revised WISC were used (WISC-R): similarities, vocabulary, arithmetic, digit span, block design, and object assembly. In NTR project YE_COG12, the full version of the Dutch WISC-R was used (12 subtests: 6 mainly verbal and 6 mainly non-verbal). The subtest scores were standardized, based on results of same-aged children in the Netherlands. No differences were made for boys and girls. Addition of the twelve standardized subtest scores resulted in full-scale IQ (total IQ). In NTR project YE_COG18, participants younger than 16 completed the full Dutch WISC-III. Verbal and nonverbal IQ scores were measured as the standardized score on 5 verbal subtests, and 5 nonverbal subtests. The WISC-III scores were standardized for the appropriate age group, based on a population sample of same-aged subjects in the Netherlands. Standardization norms were the same across the sexes.