About the Measure

Domains Omnibus
Subscales Listening comprehension, oral expression, word reading, reading comprehension, spelling numerical operations and mathematical reasoning NB not all scales available for four year olds
Target Construct Oral language: Listening comprehension Oral expression Literacy: single word reading, reading comprehension, reading speed and spelling. Numeracy: Numerical operations Mathematical reasoning
Description Assesses single word reading, reading comprehension, reading speed, spelling and numeracy
Test Authors Wechsler, D.
Publisher Pearson (2006)
Psychometry
Implementation

Implementation details

Respondent Child
Prior knowledge Required Psychologists , speech or occupational therapists, mental health professionals and health practitioners with appropriate Graduate and professional qualifications in their field of practice.
Scoring Scoring clear and transparent, need to distinguish raw scale standard scores and norms. Writing scales challenging to evaluate
Time 30 to 40 minutes
Age 4 years to 25 years and 11 months

Psychometric details

UK norms YES (from 6 years onwards only)
Norm / Criterion referenced Norm referenced
Standardisation sample 892
Reliability Reliability of age-based coefficients ranged 0.90 to 0.97. SEM of composites ranged 2.56 to 4.67. test retest ranged 0.88 to 0.95
Criterion validity Insufficient data in the public domain to evaluate
Construct validity Data available for WIAT III ranging from .6 to .82, although this varies between scales
Concurrent validity For reading and spelling WIAT correlated with SAT (0.72, 0.76), ITBS (0.78, 0.53) and CAT (0.84 , 0.74). Inter correlation between subtests was 0.33 and 0.86, and between composites 0.44 and 0.94.