and Grade 10.
Standard errors of measurement (the variability of obtained scores around the true score) were computed for PIAT-R raw scores and standard scores using split-half reliabilities. The overall median by grade for the total test was 2.0; for age levels, the mean for the test overall was 1.8.
The validity of the PIAT-R has been discussed by Benes
(19 ) who reports that the assessment included tests of both the instrument's construct validity (the extent to which performance on the test reflects the construct it was designed to measure) and its content validity (the adequacy with which test items sample the domain). Construct validity was derived from subtest and composite raw score means for successive gra
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