Selecting on Treatment: A Pervasive Form of Bias in Instrumental Variable Analyses
Selecting on Treatment: A Pervasive Form of Bias in Instrumental Variable Analyses
Instrumental variable (IV) methods are increasingly being used in comparative effectiveness research. Studies using these methods often compare 2 particular treatments, and the researchers perform their IV analyses conditional on patients' receiving this subset of treatments (while ignoring the third option of "neither treatment"). The ensuing selection bias that occurs …