Ellsberg's paradox shows that people prefer gambles with known probabilities to those where they are uncertain. Standard explanations rule out risk aversion by appealing to Savage's (1954) subjective expected utility theory but this axiomatic approach leaves open other interpretations of the...

This paper studies covariate adjusted estimation of the average treatment effect in stratified experiments. We work in a general framework that includes matched tuples designs, coarse stratification, and complete randomization as special cases. Regression adjustment with treatment‐covariate...