Applying Quality Indicators to Single‐Case Research Designs Used in Special Education: A Systematic Review

This study examined how specific guidelines and heuristics have been used to identify methodological rigor associated with single-case research designs based on quality indicators developed by Horner et al. Specifically, this article describes how literature reviews have applied Horner et al.'s quality indicators and evidence-based criteria. Ten literature reviews were examined to ascertain how literature review teams (a) used the criteria recommended by Horner et al. as meeting the 5-3-20 evidence-based practice (EBP) thresholds (five studies conducted across three different research teams that include a minimum of 20 participants) to assess single-case methodological rigor; and (b) applied the 5-3-20 thresholds to determine whether the independent variables reviewed qualified as potential effective practices. The 10 literature reviews included 120 single-case designs. This study found that 33% of the reviewed single-case designs met Horner et al.'s quality indicator criteria. Three of the literature reviews concluded that examined practices met criteria to qualify as an EBP. Recommendations related to quality indicator criteria and EBP established by the literature review teams as well as directions for future research are discussed.