A meta-analysis on the effectiveness of functional literacy interventions for adults

A significant portion of the working-age population has only rudimentary literacy skills. Many people who are functionally illiterate have problems to perform basic daily tasks and to participate in society. Given the paucity of research, the aim of this study was to evaluate the effects of adult literacy interventions using a three-level meta-regression analysis, controlling for potential moderators of effectiveness. The literature search included empirical studies with a control group design in English, French, German, Portuguese, and Spanish. 39 controlled primary studies met the inclusion criteria, including 236 effect sizes. There was a small but significant main effect on participants' literacy level (g = 0.22). Interventions with a lower frequency of weekly sessions were more effective than more intensive approaches. No significant effect on effectiveness was found for total duration, context, language of instruction, teacher-student ratio, computer use, or initial literacy level of participants. As a large proportion of the primary studies were found to be at high risk of bias, more reliable primary studies are needed to support the findings and provide a more nuanced view of the effectiveness of interventions. Nevertheless, this review provides promising evidence that adults with low literacy skills can benefit from literacy interventions.