A systematic review and meta-analysis of randomised controlled trials evaluating interventions in adult literacy and numeracy

This paper reports a systematic review of the trial literature in the field of adult literacy and numeracy. The review was undertaken to investigate the effectiveness of teaching strategies and pedagogies designed to increase adult literacy and numeracy. The objectives were to search for and locate, synthesise and quality appraise all the randomised controlled trials aiming to evaluate interventions in adult literacy and/or numeracy, published between 1980 and 2002. Fifty‐nine papers were included in the descriptive map. Twelve papers were included that contained nine randomised controlled trials. All of the trials included in the review were of high quality in the sense that they had adopted an appropriate study design for assessing effectiveness. However, within that study design many of the studies had methodological problems, for example: small sample size and lack of justification of sample size calculation; unclear method of random allocation; high attrition rate and lack of ‘intention to teach’ analysis. There was evidence of publication bias. Pooling three studies that compared teaching against no teaching showed a strong, positive and statistically significant effect on outcome. Two other studies examined the use of computer‐assisted instruction (CAI) on literacy among imprisoned adults. Pooling these two studies showed a modest but not statistically significant benefit. There is a dearth of rigorous RCTs in the field of adult literacy and numeracy. The evidence is suggestive of a benefit of adult literacy and numeracy interventions; however, because of the heterogeneity of studies, the precise role of any intervention is uncertain and this finding may be undermined by the presence of substantial publication bias. We recommend that a series of large, well‐designed and well‐conducted randomised trials should be undertaken in the field of adult literacy and numeracy.