Test identification

Name of test Wechsler Individual Achievement Test - Third UK Edition for Teachers
Previous version(s) WIAT, WIAT-II, WIAT-II UK, WIAT-II UK-T (literacy only), WIAT-III, WIAT-III UK, WIAT-III UK-T (literacy only)
Subjects Literacy
Summary A UK-normed battery of five subtests to test key aspects of literacy.

Assessment screening

Subscales Early Reading Skills, Reading Comprehension,Word Reading, Oral Reading Fluency,Spelling
Authors David Wechsler
Publisher Pearson Clinical
Test source https://www.pearsonclinical.co.uk/Education/Assessments/Achievement/wiat-iii-uk-t/wiat-iii-uk-for-teachers-wiat-iii-uk-t.aspx
Guidelines available? Yes
Norm-referenced scores. Yes
Age range 4;0 -25;11 Years
Key Stage(s) applicable to KS1, KS2, KS3, KS4, KS5
UK standardisation sample Yes
Publication date 2018
Re-norming date n/a


Validity measures available? Yes
Reliability measures available? Yes
Reason for exclusion from shortlist shortlisted

Evaluation and Appraisal

Additional information about what the test measures Literacy (word reading, fluency, comprehension and spelling skills)
Are additional versions available? WIAT-IIIUK-T (reviewed here) is a revision of WIAT-IIUKT and a version of WIAT-IIIUK. Norms and items have been updated, and new subtests added.WIAT-IIIUK was standardised on a national UK sample of 744 children and young people.WIAT-III was standardised on a national US sample of 3000 children
Can subtests be administered in isolation? Yes - separate scores (including standardised) are provided on each subtest
Administration group size Individual
Administration duration Dependent on many factors, administration times for each subtest by age and ability is presented on p8 of Examiner's manual.Typically aprroximately 25-40 minutes for the full accessment.Subtests should rarely take >10 minutes to administer, with the exception of the reading comprehension subtest which may take older participants longer.
Description of materials needed to administer test Materials included in the test kit:Examiner's manual (once familiar with procedures, the manual states that the examiner will not need to use the manual during administration),Simulus book,Oral Reading Fluency Booklet,Word card,Record form,Audio files (on USB flashdrive).Other recommended materials:Clipboard,Stopwatch/watch with second hand,Audio recorder,
Any special testing conditions? Well lit, quiet environment free from disruptions and interruptions.4-8 year olds should not have alphabet displayed in the room.

Response format

Response mode Oral/paper and pencil/manual (physical) operations
What device is required n/a
Queston format. open ended
Progress through questions adaptive

Assessor requirements

Is any prior knowledge/training/profession accreditation required for administration? Yes
Is administration scripted? Yes


Description of materials needed to score test Examiner's manual
Types and range of available scores Raw scores on each subtest;Weighted raw scores (corrected for item set);Standard score by age (40-160 - note that these are available for each subtest, and analyses of differences are provided to allow users to determine whether differences in subscale performance are significant);Percentile Rank (1-99);Age equivalent;Normal curve equivalent (1-99)Stanine (1-9);Cummulative percentages.Skills analyses can be conducted on all subtests.Users are also encouraged to provide behavioural and qualitative observations on the record form to support interpretation.
Score transformation for standard score Age standardised
Age bands used for norming 4 months
Scoring procedures complex manual scoring – training required
Automatised norming None

Construct Validity

Does it adequately measure literacy, mathematics or science?
Does it reflect the multidimensionality of the subject? Generic literacy (with specific subtests)
Construct validity comments (and reference for source) Good detail about face validity for use for diagnostic purposes. Adaptations needed for Anglicisation from WIAT-III described in detail to the examiner's manual. Construct validity is supported by moderate-strong intercorrelations between subtest age-based standard scores (.37-.99 see p189), as well as appropriate correlations with previous versions of the WIAT. 79 children aged 6;2-16;10 completed WIAT-IIIUK and WIAT-IIUK with a testing interval of 14-49 days. Correlations were high or moderate for similar subtests (word reading .81; spelling .83) and lower for dissimilar subtests (word reading and numerical operations .28). See p189 of Examiner's manual for further detail.Evidence of contrasted group validity would have further supported diagnostic use, however would not be possible from the standardisation sample due to the nature of exclusionary criteria and stratification in sampling.

Criterion Validity

Does test performance adequately correlate with later, current or past performance?
Summarise available comparisons n/a


Is test performance reliable?
Summarise available comparisons The examiner's manual indicates good reliability. Good-excellent internal consistency (coefficients .81-.97; SEM 1.5-8.35).(presented by age group and overall for each subtest).95% confidence intervals 3-16; 90% confidence intervals 2-13(presented by age group and subtest).Test-retest reliability and inter-rater reliability are not reported for the UK standardisation. Note that other measures of reliability are available that were established on the WIAT-III US standaridsation, which are likely to be somewhat transferable, but here we limit to discussion of the UK studies.

Is the norm-derived population appropriate and free from bias?

Is population appropriate and free from bias? Yes
If any biases are noted in sampling, these will be indicated here. Sampling for standardisation is excellent - WIAT-IIIUK standardisation project aimed to provide UK norms based on a census-matched sample of 744 UK children aged 4;0-25;11. Sample was recruited through a range of methods described in detail (see p180 of Examiner's Manual) and stratified by gender, age, parent educational level, race/ethnicity, geographic region. A number of exclusion criteria were included (see p180-181), meanwhile one participant with form diagnosis of learning difficulty and one participant labelled as gifted and tallented were included in each age band. Detailed information about sample demographics compared to census data are provided on p181-185


Sources Wechsler, D. (2018). Wechsler Individual Achievement Test - Third UK Edition for Teachers (WIAT-IIIUK-T): Examiner’s Manual. London, UK: Pearson Assessment.