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Many clinicians label a child as language impaired (LI) or typically developing (TD) based on arbitrary cutoff scores (1.5 SD below the mean or 1 SD below the mean) on standardized tests. However, as demonstrated in this article, many standardized tests do not even provide information about validity and reliability.
Background: This study reviewed data available in commercially available standardized test manuals to determine the validity and reliability of low test scores in diagnosing language impairment.
Methodology and Participants: Forty-three child language tests were collected and examined for evidence that they were clinically useful in identifying children with language impairment.
Conclusion: Results revealed that children with language impairment did not consistently score in the low end of the normal curve distribution of scores. A majority of test manuals reported that children identified as language impaired (LI) scored within 1.5 SD of the mean and 27% of the test manuals reported that LI children scored within 1.0 SD of the mean. Regarding psychometric data, the authors found that only 9 of the 43 tests examined provided information on sensitivity and specificity. Of those 9 that provided it, only 5 had acceptable (80% or better) accuracy. This article demonstrates that even if a test is normed on a population similar to the child’s background, a score below a certain number of SD below the mean is not a good indicator of the presence of language impairment.
Relevance to the Field: Many clinicians label a child as language impaired (LI) or typically developing (TD) based on arbitrary cutoff scores (1.5 SD below the mean or 1 SD below the mean) on standardized tests. However, as demonstrated in this article, many standardized tests do not even provide information about validity and reliability. Those that do, often have unacceptable levels of diagnostic accuracy in differentiating LI vs. TD individuals. Furthermore, those demonstrated to have acceptable levels of accuracy often have other psychometric inconsistencies such as how the children were selected for the study or issues of spectrum bias. As a result of clinicians’ reliance on standardized test scores in making a diagnosis of language impairment, large numbers of individuals (especially those from culturally and/or linguistically diverse backgrounds) have been misdiagnosed with a language disorder or are not receiving the therapy they need. Clinicians should always use clinical judgment in dynamic assessment, and gain insight from the parent interview and language sampling while being sure to compare the individual to his or her speech community to guard against misdiagnosis.
Spaulding, T. J., Plante, E., & Farinella, K. A. (2006). Eligibility criteria for language impairment: Is the low end of normal always appropriate? Language, Speech, and Hearing Services in Schools, 37, 61-72.