Calculation of Lexile Word Measures Using a Corpus-Based Model and Student Performance Data

As part of a larger project related to modeling multiple aspects of vocabulary knowledge, word difficulty measures denominated in Lexile units were calculated in a manner similar to the development of the Lexile Framework for Reading (Stenner, Horabin, Smith, & Smith, 1988; Stenner, Burdick, Sanford, & Burdick, 2007). A Lexile word measure is an estimate of the challenge a particular word will present, on average, to a particular reader during independent reading. Lexile word measures were calculated using a corpus-based, machine-learning model that was developed using student performance data from several reading tasks. The model was then used to calculate Lexile word measures for tens of thousands of words for which student performance data was unavailable.