The RD estimations mainly include the parametric estimation and the nonparametric estimation. What are the possible problems for the parameter estimation? ()

问答题Two important predictors in RD are the forcing variable and ().

问答题The DID model can be described as:Y¡ =a +βDi+yt¡+ δ(D¡.tj)+ε, where D¡ means intervention,t¡meanstime. Which parameter in the formula represents the true treatment effect