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The Prevalence of Dyslexia: A New Approach to Its Estimation

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This study proposes a new approach to operationalizing dyslexia in prevalence estimates:

  • As noted in the article, the International Dyslexia Association specifies that:
    • Dyslexia is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.
    • These difficulties are often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction.
  • To capture the "unexpected" nature of dyslexia, this study operationalizes dyslexia as a substantial difference between an individual's listening comprehension and reading (1.5 SDs).

A model-based meta-analysis and simulation based on this definition found:

  • Individuals with a substantial difference between their listening and reading comprehension can be found throughout the reading ability spectrum.
  • Some individuals with a substantial difference in listening and reading comprehension may not exhibit low reading performance.
  • In a sample of poor readers (below the 20th percentile), most readers will not be expected to have dyslexia because they will have similar levels of listening and reading comprehension ability.

Suggested Citation

National Center on Improving Literacy (2023). The Prevalence of Dyslexia: A New Approach to Its Estimation. Washington, DC: U.S. Department of Education, Office of Elementary and Secondary Education, Office of Special Education Programs, National Center on Improving Literacy. Retrieved from http://improvingliteracy.org.

References

Wagner, R. K., Zirps, F. A., Edwards, A. A., Wood, S. G., Joyner, R. E., Becker, B. J., ... & Beal, B. (2020). The prevalence of dyslexia: A new approach to its estimation. Journal of Learning Disabilities, 53(5), 354-365. DOI: 10.1177/0022219420920377.