“…This so-called "surprising inequality" (Cuadras, 1993), "quirk" (Bertrand & Holder, 1988), or "counterintuitive" (Shieh, 2001) property of multiple regression, is considered theoretically commonplace by some authors (e.g., Currie & Korabinski, 1984;Lewis & Escobar, 1986;Shieh, 2001) and empirically rare by others (Dicken, 1963;Wiggins, 1973). Related notions include "synergism" (Hamilton, 1988), "enhance-synergism" (Lipovetsky & Conklin, 2004), "enhancement-synergism" (Shieh, 2001), "suppression" (Horst, 1941;Meehl, 1945;Sharpe & Roberts, 1997) and "masking" (Kendall & Stuart, 1973, p. 331).…”