Commentary on PND at 25

The author provides commentary on the scientific enterprise of single-case meta-analysis, including experiences with and use of the percentage of nonoverlapping data statistic. The author provides a brief review and commentary on the benefits and liabilities of the PND statistic as well as other effect size metrics. The article includes general commentary about the perception and position of single-subject meta-analysis and its use to inform health insurance decision making in the field of autism. The commentary ends with predictions and recommendations for single-case meta-analysis in the next 25 years.