Lexiles

A Lexile is a unit of measurement used to describe texts and readers on a common scale that represents reading comprehension. For texts, Lexile measures describe the difficulty of reading comprehension. For readers (e.g., students), Lexile measures describe reading comprehension ability. Together, Lexile measures for texts and readers make up the Lexile Framework. This entry provides an overview of the Lexile Scale, methods for obtaining Lexile measures, and current applications of the Lexile Framework.

The Lexile Framework was developed by MetaMetrics—an educational measurement and research organization based in Durham, NC. The framework is used internationally to measure student reading comprehension and text difficulty for a variety of instructional purposes, including matching readers with texts, predicting the degree to which readers will comprehend texts with known Lexile measures, and monitoring changes in reading comprehension over time. Accordingly, the topic is relevant for educational practitioners and researchers interested in the assessment of reading comprehension and in the selection or development of assessments targeted to specific levels of reading comprehension.

Units on the Lexile Scale are reported using whole numbers followed by the letter “L.” For example, a text might have a Lexile measure of 240 L. Lexile measures for texts and readers are [Page 973]calculated on the same linear scale that ranges from below 0 L to above 2,000 L. For texts, lower numbers indicate that less ability is needed to comprehend the text, and higher numbers indicate that more ability is needed to comprehend the text. For readers, lower numbers indicate lower reading comprehension ability and higher numbers indicate higher reading comprehension ability. Because both types of Lexile measures are on a common scale, measures for texts and readers can be compared to predict the degree to which a reader will be able to comprehend a given text.

For texts, Lexile measures are calculated using a proprietary formula developed by MetaMetrics that incorporates a variety of linguistic features, including vocabulary and sentence length. Lexile measures for texts are calculated using the Lexile Analyzer computer program. For readers, Lexile measures can be calculated using several methods. Specifically, a variety of commercially produced assessments exist that can be used to obtain a Lexile reader measure. Similarly, analyses can be conducted to determine a Lexile measure based on a reader’s score on a norm-referenced or criterion-referenced assessment. Less formal methods can also be used to obtain Lexile measures for readers, including observations of students reading a text that has a known Lexile measure.

The Lexile Framework is applied internationally across a variety of contexts to describe the alignment between reading comprehension levels for texts and readers. These applications include instructional settings, test development, and the establishment of standards, including the Common Core State Standards in the United States. The Lexile Framework is available for texts in English and Spanish.

See also Rasch Model; Readability; Reading Comprehension; Reading Comprehension Assessments; Scales