How are Lexile® scores computed?

Document created by Community User on Sep 18, 2017Last modified by Community User on Sep 18, 2017
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How are Lexile® scores computed?

NWEA Research collaborated with MetaMetrics (developers of the Lexile) to develop an algorithm to calculate the Lexile measure and range from the RIT scale. The relationship between reading RIT score and the Lexile range is a simple linear transformation of the observed reading RIT score. MetaMetrics provided NWEA with a set of items that had Lexile estimates. After performing a correlation study, NWEA derived a formula to show the relationship between RIT and Lexile. This formula is not publicly available.

How can I determine a students Lexile measure from the Lexile range given in reports?

The Lexile range is a 150 point range. The student's Lexile measure is 100 points from the low end of the range, and 50 points from the high end of the range. For example, if a student's Lexile range is 200-350, their Lexile measure is 300.

It is possible for a Lexile range to go below 0. In this case, the student's Lexile range will indicate BR for Beginning Reader. See What does BR stand for in the Lexile® scores? for more information.

See also:
Lexile® is a trademark of MetaMetrics, Inc., and is registered in the United States and abroad.

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