Evaluating Reading Diagnostic Tests: An Application of Confirmatory Factor Analysis To Multitrait-Multimethod Data

Diagnostic reading tests, in contrast to achievement tests, claim to measure specific components of ability hypothesized to be important for diagnosis or remedia-tion. A minimal condition for demonstrating the con-struct validity of such tests is that they are able to dif-ferentiate validly between the reading traits that they claim to measure (e.g., comprehension, sound dis-crimination, blending). This condition is rarely tested, but multitrait-multimethod (MTMM) designs are ideally suited for this purpose. This is demonstrated i