Many public policies, and especially health policies, are aimed at modifying individual behavior. This is particularly true of anti smoking policies. However, health behavior is highly heterogeneous, and so are individual responses to public policies such as taxes or restriction on use. We...

Difference in differences require that 0% of observations are treated in the control group and during period 0 (no "always takers") and 100% in the treatment group in period 1 (no "never takers"). Sometimes, the treatment rate increases more in the treatment than in the control group but there...

We show that the Wald statistic still identifies a causal effect if instrument monotonicity is replaced by a weaker condition, which states that the potential propensities to be treated with or without the instrument should have the same distribution, conditional on potential outcomes. This...

We know that instrumental variable (IV) estimates a causal effect if the instrument satisfies a monotonicity condition. When this condition is not satisfied, we only know that IV estimates the difference between the effect of the treatment in two groups. This difference could be a very...

We explore the willingness-to-pay (WTP) to fight climate change in a choice experiment. Since tree planting prevents climate change, subjects are offered to choose between receiving a high amount of money or receiving a lower amount of money plus participating to tree planting action. This...

Difference in differences (DID) require that the treatment rate is equal to 0% in the control group and during period 0 (no “always takers”) and to 100% in the treatment group in period 1 (no “never takers”). Sometimes, treatment rate increases more in the treatment than in the control...