Meta-Analysis of Incremental Rehearsal Using Phi Coefficients to Compare Single-Case and Group Designs

[The current study meta-analyzed single-case design (SCD) and group research regarding incremental rehearsal (IR). We used phi to meta-analyze data from 19 IR studies. Data from the SCD studies resulted in a nonoverlap of all pairs (NAP) score of 98.9 % (95 % CI = 97.6-100 %), which resulted in a weighted phi of.77 (95 % CI =.69-.83). The group research data resulted in a median d of 1.67 (95 % CI = 1.43-1.91), which converted to a weighted phi of.63 (95 % CI =.39-.87). Results suggested that using NAP to compute a weighted phi from SCD research led to a coefficient that was not significantly different from the weighted phi based on group studies z =.46, p > .05, and there was not significant heterogeneity among the effect sizes (Q (k = 17, df = 16) = 11.73, p > . 05, I 2 = 0). Efficiency data resulted in a weighted phi of -.22 (95 % CI = -.79 to.34), which suggested a small effect when comparing the efficiency to other approaches, but the studies used different data to determine efficiency. Suggestions for future research are included.