Application of the percentage of non-overlapping data (PND) in systematic reviews and meta-analyses: A systematic review of reporting characteristics

Abstract

The percentage of non-overlapping data (PND; Scruggs, Mastropieri, & Casto, 1987) is one of several outcome metrics for aggregating data across studies using single-subject experimental designs. The application of PND requires the systematic reviewer to make various decisions related to the inclusion of studies, extraction of data, and analysis and interpretation of data. The purpose of this systematic review was to determine the reporting characteristics associated with the application of PND in systematic reviews and meta-analyses. The authors engage in a discussion of the reporting characteristics found in the data set and propose several directions for future applications and reporting of PND in systematic reviews.

Keywords:

• Systematic review
• mata–analysis
• percentage of non–overlapping data
• reporting characteristics

Acknowledgments

This project was in part supported by a Field-Initiated Development Grant from the National Institute on Disability and Rehabilitation Research (NIDRR), U.S. Department of Education (#H133G070150-08) to Ralf W. Schlosser. The authors, however, bear sole responsibility for the content of this paper and funding by NIDRR does not imply that the opinions expressed in this report are those of the agency.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Notes

Notes

1.  Obviously, tabular data can be converted into a graph by the systematic reviewer and therefore afford PND calculation.

2.  Graham (2006) only included multiple baseline designs and hence no other conventions were necessary.

3.  The systematic review by Graham (2006) only included MBDs, and so orthogonal contrasts are not applicable.

4.  It may be that not all reviews included comparative designs and therefore conventions for ATDs or AATDs would not be expected. If that were the case, these exclusion criteria would need to be spelled out together with the inclusion criteria. It is unlikely that all of the reviews (except the two mentioned), meant to exclude such designs from their review.

Articles included in the analysis are indicated with an asterisk(*)