“…More recently, nonparametric and semiparametric quantile regression models have attracted a great deal of research attention due to their greater flexibility than tightly specified parametric models. See, for example, Chaudhuri (1991), He and Shi (1996), Chaudhuri, Doksum and Samarov (1997), He, Ng and Portnoy (1998), Yu and Jones (1998), Koenker, Ng and Portnoy (1998), He and Ng (1999), He and Liang (2000), He and Portnoy (2000), Honda (2000Honda ( , 2004, Khindanova and Rachev (2000), Cai (2002a), De Gooijer andGannoun (2003), Kim (2007), Lee (2003), Yu and Lu (2004), Horowitz and Lee (2005), Cai and Xu (2008), Cai, Gu and Li (2009) and references therein for recent statistics and econometrics literature.…”