5.6 Examples & further reading

• Can Nonrandomized Experiments Yield Accurate Answers? A Randomized Experiment Comparing Random and Nonrandom Assignments (Shadish, Clark, and Steiner 2008)
• The importance of covariate selection in controlling for selection bias in observational studies (Steiner et al. 2010)
• Randomizr package for random assignment in R

References

Shadish, William R, M H Clark, and Peter M Steiner. 2008. “Can Nonrandomized Experiments Yield Accurate Answers? A Randomized Experiment Comparing Random and Nonrandom Assignments.” J. Am. Stat. Assoc. 103 (484): 1334–44.

Steiner, Peter M, Thomas D Cook, William R Shadish, and M H Clark. 2010. “The Importance of Covariate Selection in Controlling for Selection Bias in Observational Studies.” Psychol. Methods 15 (3): 250–67.