ABSTRACT
Most psychological researchers realize at least one way in which sample size planning is important. Namely, if their study fails to have suffi cient statistical power, they run an increased risk of not being able to publish their work. Despite this awareness, literature reviews usually show that underpowered studies persist. In fact, underpowered studies permeate the literature not only in psychology (e.g., Bezeau & Graves, 2001; ClarkCarter, 1997; Kosciulek & Szymanski, 1993; Mone, Mueller, & Mauland, 1996; Rossi, 1990; Sedlmeier & Gigerenzer, 1989) but in other disciplines as well. For example, recent reviews in such areas of medicine as head injury (Dickinson, Bunn, Wentz, Edwards, & Roberts, 2000), orthopedics (Freedman & Bernstein, 1999), rheumatology (Keen, Pile, & Hill, 2005), stroke (Weaver, Leonardi-Bee, Bath-Hextall, & Bath, 2004), and surgery (Maggard, O’Connell, Liu, Etzioni, & Ko, 2003) show frequent instances of inadequate statistical power.
