Ariel Linden & Paul R. Yarnold
Linden Consulting Group, LLC & Optimal Data Analysis, LLC
Data from the National Supported Work (NSW) randomized experiment have been used frequently over the past 30 years to demonstrate the implementation of various non-experimental methods for drawing causal inferences about treatment effects. In the present study we reanalyze the NSW data using ODA and compare results with those estimated using t-tests. Statistical results were largely consistent between methods, however ODA found 22.2% (2 of 9) preintervention characteristics to be imbalanced. Given that ODA avoids assumptions required of parametric methods, and is insensitive to skewed data and outliers, ODA should be considered the preferred approach when evaluating data from randomized experiments.