Developing a Longitudinal Scale for Language: Linking Across Developmentally Different Versions of the Same Test

Purpose Many language tests use different versions that are not statistically linked or do not have a developmental scaled score. The current article illustrates the problems of scores that are not linked or equated, followed by a statistical model to derive a developmental scaled score. Method Using an accelerated cohort design of 890 students in Grades 1–5, a confirmatory factor model was fit to 6 subtests of the Test of Language Development–Primary and Intermediate: Fourth Edition (Hammill & Newcomer, 2008a, 2008b). The model allowed for linking the subtests to a general factor of language and equating their measurement characteristics across grades and cohorts of children. A sequence of models was fit to evaluate the appropriateness of the linking assumptions. Results The models fit well, with reasonable support for the validity of the tests to measure a general factor of language on a longitudinally consistent scale. Conclusion Although total and standard scores were problematic for longitudinal rela...