“…Several smoothing methods are considered in the literature for quantile regression: local polynomial in Chaudhuri (), Honda (), and Cai & Xu (); smoothing splines in He, Ng, & Portnoy (); B‐splines in He & Shi () and Kim (); and penalized B‐splines (P‐splines) in Bollaerts, Eilers, & Aerts () and, Andriyana, Gijbels, & Verhasselt, ; Andriyana, Gijbels, & Verhasselt, . There is also a vast literature on variable selection in VCMs, when the focus is on quantile estimation (e.g., Noh, Chung, & Van Keilegom, ; Tang, Wang, & Zhu, ).…”