Technical characteristics of the peabody individual achievement test as a function of item arrangement and basal and ceiling rules

The effects that item order and basal and ceiling rules have on test means, variances, and internal consistency estimates for the PIAT mathematics and reading recognition subtests were examined. Seven items on the math subtest and one item on the reading recognition subtest were significantly easier or harder than their test placement indicated. The use of basal and ceiling rules had a pronounced effect on the means, variances, and reliabilities on the multiple choice math subtest, while the rules' effects on the reading recognition subtests were minor. Item order also affected scores on the math subtest.