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The Wechsler Individual Achievement Test, Second UK Edition (WIAT-II)

The WIAT-II is a measure of basic academic skills, designed for children aged between 4 and 16 years 11 months. It covers 4 main domains of skills, reading, mathematics, written language and oral language. Each of these domains is further divided into sub-domains. Reading includes, word reading, pseudo word decoding and reading comprehension. Mathematics includes numerical operations, and mathematic reasoning. Written language includes spelling and written expression. Finally, oral language includes listening comprehension and oral expression. The WIAT-II UK Edition was standardised on 892 individuals in the UK. It features comprehensive nominative information including age-based standard scores, percentile, stanines, normal curve and age equivalent for each subset.  As for the other tests, the WIAT-II has been standardised to have a mean of 100 with a standard deviation of 15, covering a range of 40 to 160.

For typically developing (TD) children, the testing time varies according to age from 45 minutes for ages 4-5, approximately 90 minutes for ages 6-11 and around 2 hours for ages 7-16.

The test comes with extensive guidelines on administration and scoring. It is essential that the right procedure is adopted, and that a starting point suitable for the chronological age and the estimated developmental stage of the child is selected. Suitable reverse and discontinuing rules should be applied in order to obtain an accurate measurement of the child’s performance. The scoring can be conducted using a range of conversing tables, specific to the participant’s age or alternatively by entering the raw scores into the WIAT-II scoring software provided with the test. This was the option selected for the current study.

The reliability of the test depends on the testing conditions (including the administration and scoring) and the children’s presentation in terms of behaviour, attention and skills. It was reported that two studies have been conducted involving a total of 2180 examinees’ responses, to evaluate the inter-scorer reliability and that reliability factors ranging from 0.94 to 0.98 across ages were identified.

The validity of the WIAT-II was estimated from correlation with other assessments such as the Wide Range Achievement Test (Third Edition), the Wechsler scale and the Differential Ability Scales. The correlation for the corresponding sub-set pairs ranged from low (0.25) to moderately high correlation (0.85), depending on the sub-set pairs. It was thought that this reflects differences in the subsets contents. It is important none the less to keep these values in mind when interpreting the results.

The WIAT-II provides norminative data obtained from individuals presenting with a range of conditions, ADHD, learning difficulties, emotional disturbances, hearing impairments and speech and language impairments. The reliability factors for these groups of individuals were not given in the WIAT-II manual.


Quick Facts

Administer To                                 Individuals from 4 years to 16 years 11 months

Completion Time                           90-240 min

Formats                                             Semi-structured assessment

Scoring Options                              Hand Scoring (immediately after the session)

Norms                                               2180+ children

ADHD, Language impairment, hearing impairment, mental retardation, emotional disturbances