“…However, the estimation of error density is important to understand the residual behavior and to assess the adequacy of error distribution assumption (see for example, Akritas and Van Keilegom, 2001;Cheng and Sun, 2008); the estimation of error density is also useful to test the symmetry of the residual distribution (see for example, Ahmad and Li, 1997;Dette et al, 2002;Neumeyer and Dette, 2007); the estimation of error density is important to statistical inference, prediction and model validation (see for example, Efromovich, 2005;Muhsal and Neumeyer, 2010); and the estimation of error density is also useful for the estimation of the density of the response variable (see for example, Escanciano and Jacho-Chávez, 2012). In the realm of financial asset return, an important use of the estimated error density is to estimate value-at-risk for holding an asset.…”