“Evidence Based” — But does it work?

child strugging with homework

Parents who are seeking help for their dyslexic kids usually have one question uppermost in their minds: will it work?

Parents and teachers are often encouraged to look for a dyslexia program that is “evidence-based”, with little guidance about what that phrase means. Parents might naturally assume that “evidence-based” means that a program has been proven to work for dyslexic children. But the reality is different — often the research evidence is sparse, and may be limited to one or two studies showing that children receiving a specific intervention generally showed small or moderate improvement in one or two skills taught.

Due to reasons that have more to do with public relations than science, the phrase “evidence-based” is often tied to phonics-based tutoring programs, although much of the “evidence” actually shows that these programs are ineffective for large numbers of dyslexic children.

For example, research findings indicate that about 20 to 40% of children with dyslexia fail to improve their reading skills during a phonics-based intervention.1 2 These children are sometimes labeled as “treatment resisters” or “nonresponders”— but it is not the children’s fault that the intervention is ineffective.

Even among the children who do “respond” with improved phonetic-decoding skills, the research evidence does not show meaningful improvement with real-word reading skills or comprehension.3

Further, while there are many studies showing short-term improvement in some skills from phonics-based interventions, there is little evidence showing long-term benefits.  One meta-analysis of 71  interventions showed that effect sizes decreased over time, and that only a small effect was maintained in the long term. 4 In other words, even when the students appear to benefit from tutoring, the gains often do not persist.

So how can a parent or teacher know whether a particular child will be one of the 20-40% who will not benefit from phonics-based teaching? 

One study tried to answer this question by looking at factors that might predict long-term success among a group of 80 dyslexic fourth-graders given a 50-week phonics-based intervention. 5

The good news was that the researchers were able to identify at least one important factor that could help predict which children were more or less likely to benefit from the intervention.  On measures of pseudoword reading – or phonetic decoding using made-up words – the results could be predicted by the level of ability prior to the beginning of the intervention. The children who had the most difficulty with this task at the outset were also the least likely to benefit from the intervention.

The bad news was that even the children who did benefit from the tutoring did not do particularly well: “at the long-term measurement up to a year after the intervention, children with dyslexia were still significantly behind on both word and pseudoword reading fluency compared to typical readers.”

This finding was not unusual; the researchers noted that their results were in “accordance with a number of reading intervention studies that show that reading fluency is more difficult to remediate than reading accuracy.”

So what do these studies mean for parents and educators?

mother helping child reading book

To start with, it is important to look beyond the label “evidence-based” and instead focus on the individual needs of the child.  Even with improved phonetic decoding skills, many dyslexic students continue to find reading difficult and effortful– the end goal should be reading fluency along with strong comprehension and retention.

To become good readers, students will need much more than phonics. They will need to develop a strong reservoir of sight words that they can recognize automatically without decoding. They will need to understand morphologic concepts – the meanings associated with letter sequences and word parts. They will need to develop the ability to read passages quickly and accurately, both silently and orally.  They will need to develop a strong vocabulary, knowing the meanings and pronunciations of words they are likely to encounter in print.

Dyslexic children will lose ground if too much time is spent with phonics teaching, while other facets of reading instruction are ignored.  The kids who struggle the most with learning to read through phonics are also the ones who unfortunately are at the greatest risk of being placed in long-term phonics-based tutoring programs, despite being the least likely to benefit.   So one good starting point would be to avoid that placement in the first place.

This may seem counter-intuitive, especially for teachers or parents who see mastery of phonics as a necessary precursor to reading.  But brain research shows that children don’t learn in a linear or stepwise fashion; that is especially true for dyslexic learners, who tend to rely more on intuitive, top-down, right-brained learning strategies.  These students may learn better with an approach that helps them draw mental connections with different aspects of the words, and employ multiple creative and problem-solving strategies. That is why some leading dyslexia researchers advocate integrated, multi-faceted, and meaning-based approaches. 6

And it is why Davis methods have always been built around how words look and what they mean, as well as how they sound.

Research Update:

The researchers who authored the predictive study above subsequently reported results of longer-term follow-up in two successive studies. In one, they explored longer-term outcomes of dyslexic children who had received a systematic, phonics-based reading intervention in grades 2-4. Unfortunately, these children showed very little development in word reading accuracy or fluency through grades 5-6. Despite the intensive early intervention, the gap in reading fluency skills between children with and without dyslexia widened over the years.7

In another study, the researchers compared the effects of semantic (meaning-based) priming on word-recognition skills of dyslexic and typically-developing 6th graders. They found that reading efficiency was positively correlated with semantic priming among dyslexic children only, Further, the dyslexic children with better reading skills showed significantly stronger semantic priming effects. This provides further evidence of the importance of meaning-based strategies for dyslexic learners.8

An earlier version of this article was published originally in October 2017. It has been revised and updated to include more recent research findings.


  1. Torgesen, J. K. (2000). Individual differences in response to early interventions in reading: The lingering problem of treatment resisters. Learning Disabilities Research & Practice, 15(1), 55–64.
  2.  Al Otaiba, S., & Fuchs, D. (2002). Characteristics of children who are unresponsive to early literacy intervention: A review of the literature. Remedial and Special Education, 23(5), 300–316.
  3. Joseph K. Torgesen, Richard K. Wagner & Carol A. Rashotte (1997) Prevention and Remediation of Severe Reading Disabilities: Keeping the End In Mind, Scientific Studies of Reading, 1:3, 217-234
  4. Suggate, S. P. (2014). A meta-analysis of the long-term effects of phonemic awareness, phonics, fluency, and reading comprehension interventions. Journal of Learning Disabilities, 49(1), 77–96.
  5. Van der Kleij, S.W., Segers, P.C.J., Groen, M.A., Verhoeven, L.T.W. (2017) Response to intervention as a predictor of long-term reading outcomes in children with dyslexia. Dyslexia, Vol. 23, p.268-282.
  6. Wolf, Maryanne and Tamir Kazir-Cohen. (2009) Reading Fluency and Its Intervention. Scientific Studies of Reading 5(3), 211-239.
  7. Van der Kleij, S. W., Segers, E., Groen, M. A., & Verhoeven, L. (2019). Post-treatment reading development in children with dyslexia: the challenge remainsAnnals of dyslexia69(3), 279–296.
  8. Van der Kleij, S. W., Groen, M. A., Segers, E., & Verhoeven, L. (2019). Enhanced semantic involvement during word recognition in children with dyslexiaJournal of experimental child psychology178, 15–29.