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

Internal consistency:

Strong inter-item consistency within subtests with average reliability co-efficients ranging from .80 to .98

Test-retest:

Adequate stability across time and ages with relatively small differences ranging from 1 to 4 standard score points.

Average stability co-efficients ranging from .85 to .98 across the three age groups tested (6 to 9, 10 to 12 and 13 to 19 years).

Interscorer agreement:

Strong interscorer reliablility between pairs of scores ranging from .94 to .98 across ages, with an overall reliability of .94

 
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