Distribution-based approaches
Distribution-based approaches estimate RD thresholds based on statistics that describe the variation and precision of scores, such as a scale’s standard deviation (SD) and reliability, to assess the amount of difference or change on a measure that cannot be explained by measurement error and is considered to reflect a clinically meaningful treatment effect. Three distribution-based statistics were used in the estimation of RD thresholds on all NIS and NIS-LL scores: effect size (ES), standardized response mean (SRM), and standard error of measurement (SEM). The mean of these estimates was then used as the recommended RD threshold.The ES has long been used to interpret the magnitude of difference between groups or change over time in education, psychology, and health outcomes research [The SRM is another statistic used to interpret group differences and change over time, this time measured against the standard deviation of change from baseline (SDThe SEM captures measurement error of a scale based upon variability of scores (SD