(Effect) Size Matters: And So Does the Calculation

Olive, M. L., & Franco, J. H. (2008). (Effect) size matters: And so does the calculation. The Behavior Analyst Today, 9(1), 5-10. http://dx.doi.org/10.1037/h0100642

The purpose of this paper is to present the types of measures that may be used to describe intervention effects from single subject designs. A regression approach and several non-regression approaches are described. Non-regression approaches include Standard Mean Difference, Percentage of Non-Overlapping Data, Percent Reduction, and Percentage Exceeding the Median. Researchers are encouraged to combine a non-regression measure along with considerations of methodological rigor and visual analysis to fully appreciate the contributions of single subject intervention data.

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