Lexile scores are assigned based on individual words and sentence length, rather than qualitative analysis of the content.

[2] According to LightSail Education, about half of U.S. students in grades 3-12 receive a Lexile measure each year.

According to MetaMetrics, text measures are evaluated through the "Lexile Analyzer", a computer program that assigns a score based on vocabulary and syntax.

[13] According to MetaMetrics, Lexile text measures can assist in selecting appropriately challenging materials for readers.

From 1984 to 1996, MetaMetrics received funding through five grants from Small Business Innovation Research, obtained through the National Institutes of Health, to develop a measurement system for reading and writing.

The study found that the students could read texts at their assigned Lexile scores (93%), but also noted that 43% of the sampled books were below a basic standard for 2nd grade.

[5] The review affirmed the value of sentence length and word frequency as measures of complexity but also stated that these metrics are an estimated correlate of readability.

The standards also note that quantitative methods like Lexile may underestimate the challenges of complex narrative fiction and that qualitative measures should be prioritized for students in grade 6 and above.