Before revision:  We derive finite-sample optimal estimators and confidence intervals (CIs) under the assumption of normal errors when the conditional mean of the outcome variable is constrained only by nonparametric smoothness and/or shape restrictions .
After revision:  We derive finite-sample optimal estimators and confidence intervals (CIs) under the assumption of normal errors when the conditional mean . We also derive the minimum smoothness conditions on the conditional mean that are necessary for \sqrt{n .