Boundary bias (scaled by 104) estimated as the mean over 100 realisations.

The true density at the boundary is fX(−2) = 0.0427 and fX(2) = 0.1450 for test case 13, fX(0) = fX(1) = 0 for test case 14, and fX(0) = 0 for test case 15. For the semiparametric estimators and test cases 14 and 15, the upper row refers to models without boundary terms and the lower row to models allowing for logarithmic boundary terms at any boundary point. The best method is indicated in bold.