“…Meta-analyses have reported significant effects, on the order of 40% of intention and 30% of behavior typically accounted for (Crano & Prislin, 2006). Use of the TRA in health research has been especially prevalent (Cooke & French, 2008;Hackman & Knowlden, 2014;Plotnikoff, Costigan, Karunamuni, & Lubans, 2013;Tyson, Covey, & Rosenthal, 2014). Augmenting the TRA is a common approach and is often used as a test of the adjunct variable's effect based on the TRA's sufficiency claim, which states that attitudes and norms should explain most if not all of the variance in behavioral intention (Conner & Armitage, 1998).…”