Phonological Awareness Intervention Research: A Critical Review of the Experimental Methodology

The methodological rigor of 39 studies of phonological awareness intervention was evaluated based on internal and external validity criteria. The internal validity criteria encompassed general design characteristics, measurement, and statistical treatment, while the external validity criteria included research hypotheses, participant selection and description, and generalization and maintenance measures. The most serious methodological flaws observed in many of the studies were (a) nonrandom assignment of participants to conditions; (b) failure to control for Hawthorne effects by providing alternate interventions to control groups; (c) insufficient or nonexistent assurance of fidelity of treatment; (d) poor measurement sensitivity; and (e) inadequately described samples. Only seven studies met two thirds or more of all the evaluative criteria, although all of these investigations demonstrated at least one fatal flaw. The reported findings are compared with those of two similar methodological reviews. Suggestions for improvement of future intervention research are provided.