The Wechsler Individual Assessment Test is a bit different than some of the more frequently referenced Wechsler Tests. The WIAT is focused on academic skills as opposed to measuring intelligence. The WIAT is commonly used in settings such as:
- Residential treatment facilities
- Private medical practices
Depending on the subject, the results can be used for a variety of purposes including identifying academic strengths and weaknesses, educational placement, and the identification of learning disabilities (often in conjunction with the WAIS-IV or WISC-IV tests).
The original Wechsler Individual Achievement Test was published in 1992 by David Wechsler and was designed to assess the academic capabilities of people between the ages of 4 and 85. The test was revised first in 2005 as the Wechsler Individual Assessment Test Second Edition (WIAT-II) and again in 2009 to the Wechsler Individual Achievement Test Third Edition (WIAT-III) which is still in use as of 2018. The WIAT-III was designed for subjects between the ages of 4 to 50 years and 11 months.
There are sixteen subtests included in the WIAT, and they are broken down to measure listening, speaking, reading, writing, and mathematical skills. The subtests involved in the test include:
- Listening comprehension – The subject is told a series of vocabulary words and points to pictures that represent the words. This is followed by a listening exercise where the subject answers questions about short passages that are read to them.
- Oral expression – The subject has to verbalize the concepts of pictures they are shown and says words from given categories and repeats sentences.
- Reading comprehension – The subject reads short passages and answers open-ended questions.
- Word reading – The subject is required to read words that become increasingly difficult as they progress through the list. The subject must verbalize the words aloud.
- Pseudoword decoding – This is the same as word reading except that the subject must verbalize letters which are nonsense rather than actual words.
- Oral reading fluency – The subject is required to read provided passages aloud and then respond to questions to gauge their comprehension of the passages.
- Sentence composition – The subject must take multiple sentences and combine them into a single sentence that maintains the meaning of the original sentences. Another section of this subtest requires the subject to construct meaningful sentences using a required set of words.
- Essay composition – The subject is given ten minutes to write an essay.
- Spelling – The subject spells specific words from sentences that are dictated to them.
All of the math-related subtests’ content are based on the grade and ability of the test subject.
- Math problem-solving – This subtest includes math problems related to basic skills and everyday applications.
- Numerical operations – The subject solves untimed written problems covering basic numerical skills, integers, geometry, algebra, and calculus.
- Addition math fluency – The subject has a sixty-second-time limit to solve written addition problems.
- Subtraction math fluency – The subject has a sixty-second-time limit to solve written subtraction problems.
- Multiplication math fluency – The subject has a sixty-second-time limit to solve written multiplication problems.
Like many other tests, participants tend to ask questions about scoring before they take the test. So, what is a good score on the Wechsler Intelligence Achievement Test? The average score, like the other Wechsler tests, is 100, with a standard deviation of 15. So, if “good” is defined by above average, a score over 115 could be safely assumed to be above average. Test scores can range from 40 to 160, though in the standardization sample performed in the United Kingdom, 95% of participants scored between 70 and 130. In terms of reliability, internal testing consistency falls between 0.8 and 0.98. If you’re not statistically inclined, using Cronbach’s aIpha as a guide tells us that these results range from good to excellent in terms of reliability. you’re not statistically inclined, that’s quite high.
United States vs. United Kingdom
There are some minor differences between the WIAT in the US compared to the UK. The differences include different picture items in the visual subtests as well as changes for regional spelling differences.