Measuring Reading Comprehension with the Lexile Framework

Abstract

This paper shows how the concept of general objectivity can be used to improve behavioral science measurement, particularly as it applies to the Lexile Framework, a tool for objectively measuring reading comprehension. It begins with a dialogue between a physicist and a psychometrician that details some of the differences between physical science and behavioral science measurement. Building on these distinctions, a definition of measurement is offered that describes what goes on in the physical sciences and represents an attainable ideal of what should go on in the behavioral sciences. This definition of measurement is formalized in an equation that turns out to be the Rasch model, with the important difference that indicant calibrations are obtained via theory, not data. Through the use of theory-based calibrations, a generally objective estimation of the measure parameter in the Rasch model is achieved. The paper then examines the differences between local objectivity obtained with the Rasch model and general objectivity obtained with a theory-enhanced version of that model. Next, it reports on a 10-year study of reading comprehension measurement that implemented the concept of general objectivity through the development of the Lexile Framework. Finally, it summarizes several of the benefits of objective measurement and general objectivity as they might be realized in the measurement of constructs other than reading comprehension. Contains 52 references, and 4 tables and a figure of data.