“…While the classic topic of nonparametric inference is well-established and has been the subject of many reviews (for instance, Härdle and Linton (1994), Pagan and Ullah (1999), Ichimura and Todd (2007), Li and Racine (2007), Horowitz (2009)), the topic is still receiving considerable ongoing attention (Lewbel and Linton (2002), Giné and Nickl (2010), Low (1997), Cai, Low, and Xia (2013), Hoffmann andNickl (2011), Cai, Low, andMa (2014), Armstrong (2014), Chernozhukov, Chetverikov, and Kato (2014), Calonico, Cattaneo, and Titiunik (2014), Armstrong and Kolesár (2014), Calonico, Cattaneo, and Titiunik (2015), Pinkse (2001), Su and Ullah (2008), among many others), due to numerous open problems that have not found theoretical or practical solutions. One of these remaining problems is the following undesirable dilemma.…”