Thompson et al. article
Thompson, B., Diamond, K. E., McWilliam, R., Snyder, P., & Snyder, S. W. (2005). Evaluating the quality of evidence from correlational research for evidence-based practice. Exceptional Children, 71(2), 181–194.
Abstract by authors:
Only true experiments offer definitive evidence for causal inferences, but not all educational interventions are readily amenable to experiments. Correlational evidence can at least tentatively inform evidence-based practice when sophisticated causal modeling or exclusion methods are employed. Correlational evidence is most informative when exemplary practices are followed as regards (a) measurement, (b) quantifying effects, (c) avoiding common analysis errors, and (d) using confidence intervals to portray the range of possible effects and the precisions of the effect estimates.