Reading research for students with LD: a meta-analysis of intervention outcomes

The present article provides a meta-analysis of instructional research with samples of children and adolescents with learning disabilities in the domains of word recognition and reading comprehension. The results of the synthesis showed that a prototypical intervention study has an effect size (ES) of .59 for word recognition and .72 for reading comprehension. Four important findings emerged from the synthesis: (a) Effect sizes for measures of comprehension were higher when studies included derivatives of both cognitive and direct instruction, whereas effect sizes were higher for word recognition when studies included direct instruction; (b) effect sizes related to reading comprehension were more susceptible to methodological variation than studies of word recognition; (c) the magnitude of ES for word recognition studies was significantly related to samples defined by cutoff scores (IQ > 85 and reading < 25th percentile), whereas the magnitude of ES for reading comprehension studies was sensitive to discrepancies between IQ and reading when compared to competing definitional criteria; and (d) instructional components related to word segmentation did not enter significantly into a weighted least square hierarchical regression analysis for predicting ES estimates of word recognition beyond an instructional core model, whereas small-group interactive instruction and strategy cuing contributed significant variance beyond a core model to ES estimates of reading comprehension. Implications related to definition and instructional components that optimize the magnitude of outcomes are discussed.