by them (Chou, Grant, & Dawson, 1996; Klein et al., 2004; Laitinen, Power, Ek, Sovio, & Jarvelin, 2002; Pingitore, Dugoni, Tindale, & Spring, 1994; Poirier et al., 2006; Rohde et al., 2007; Stein, 1999). Although controlling for all possible contributing variables is a rigorous and appropriate approach to examining causal relationships, we felt it would mask some genuine associations in this study of population associations between the conditions of interest.
