Comparison of sampling techniques in the measurement of children's morphological development.

Sixty children ranging in age from 66 to 78 months were administered the Berry-Talbott Exploratory Test of Grammar and the Grammatic Closure subtest of the Illinois Test of Psycholinguistic Development. The verbal responses obtained of each child from each sampling technique were compared on matched grammatical items. A correlation coefficient between the two test group means indicated only moderate correlation. An analysis of the matched grammatical items (40 comparisons) showed a higher correct response frequency for the Grammatic Closure items than for the Berry-Talbott items. However, children who did achieve correct responses to the Berry-Talbott items almost always achieved success with the Grammatic Closure test items. Success on the Grammatic Closure items did not assume success with the Berry-Talbott items. Various hypotheses are offered to explain differences in response patterns.