Clinicians are confronted with a wide range of norm-referenced tests designed to evaluate preschool language skills. This article approaches test selection from a data-based perspective. Twenty-one tests of language skills that included norms for children ages 4 and 5 years were reviewed for information on 10 psychometric criteria. Only 38% of these tests met half or more of the 10 psychometric criteria employed by McCauley and Swisher (1984a) in their review. Four tests that met a relatively high number of psychometric criteria (6 or more) were administered to 20 preschool children with specific language impairment and 20 age-matched controls. High interexaminer reliability was obtained for all tests. All tests had low correlations with a measure of nonverbal skills. Only one of the four tests provided acceptable accuracy in discriminating between the children with normal and the children with impaired language in our sample. Our empirical examination of four tests revealed that even tests that pass relatively high numbers of psychometric criteria may not be precise discriminators of normal and impaired language in 4- and 5-year-old children, indicating the need to complement psychometric review with data-based validation procedures.

These results support the notion of attention difficulties in preschool children with SLI and suggest separate attentional capacities for different stimulus modalities.

This study examined the empirical evidence for using four vocabulary tests (Peabody Picture Vocabulary Test-III [Dunn & Dunn, 1997], Receptive One-Word Vocabulary Test [Gardner, 1985], Expressive Vocabulary Test [Williams, 1997], Expressive One-Word Vocabulary Test-Revised [Gardner, 1990]) to screen or identify specific language impairment (SLI) in preschool-age children. Tests were administered to 31 4- and 5-year-old children with SLI and 31 age-matched controls with normal language (NL). All children spoke General American English. Despite moderate to strong inter-test correlations, no test was a strong identifier of SLI. The group with SLI scored lower than the NL group on each test; however, the individual scores of children with SLI typically fell within the normal range. Vocabulary tests are frequently administered to determine whether a child's language skills require further evaluation (screening), as a method of identifying SLI in children, or simply to describe aspects of language functioning. These purposes for administering a vocabulary test require various forms of empirical evidence in support of their use. Our data support construct validity for the four vocabulary tests examined, but do not support their use for identification purposes. Clinicians must apply a degree of sophistication in evaluating the evidence presented for test validity relative to the purposes for which the test will be administered. Unfortunately, although many test manuals offer inter-test correlations or statistically significant group differences as evidence of construct validity, they often omit data that would support common clinical uses, such as screening or identification.

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The results support the use of highly variable input in a therapeutic context to facilitate grammatical morpheme learning.