Given That Nonexperimental Datasets Are Likely to Have Treatments That

Multiple Choice

Given that nonexperimental datasets are likely to have treatments that have not been randomly assigned, what is likely to contribute to difference in average outcomes between groups with different treatment levels?

A) Some of those differences are driven by a selection bias
B) Non-normality of the underlying population distribution
C) Skewed perceptions of quality
D) Heteroskedasticity