Theory Testing Using Quantitative Predictions of Effect Size

Traditional Null Hypothesis Testing procedures are poorly adapted to theory testing. The methodology can mislead researchers in several ways, including: (a) a lack of power can result in an erroneous rejection of the theory; (b) the focus on directionality (ordinal tests) rather than more precise quantitative predictions limits the information gained; and (c) the misuse of probability values to indicate effect size. An alternative approach is proposed which involves employing the theory to generate explicit effect size predictions that are compared to the effect size estimates and related confidence intervals to test the theoretical predictions. This procedure is illustrated employing the Transtheoretical Model. Data from a sample ( N = 3,967) of smokers from a large New England HMO system were used to test the model. There were a total of 15 predictions evaluated, each involving the relation between Stage of Change and one of the other 15 Transtheoretical Model variables. For each variable, omega-squared and the related confidence interval were calculated and compared to the predicted effect sizes. Eleven of the 15 predictions were confirmed, providing support for the theoretical model. Quantitative predictions represent a much more direct, informative, and strong test of a theory than the traditional test of significance.     

Margaret F. Washburn (1871–1939): First Woman Ph.D. in Psychology

Margaret Floy Washburn was one of the first generation of leading psychologists trained in America and became an eminent and influential psychologist during the first third of the 20th century. She was recognized for significant contributions in theory development, experimental work, teaching, and professional service, but this paper focuses on her activities as director of the psychology program at Vassar College and author of the classic text in comparative psychology, The Animal Mind . Although full biographical details are not given, a listing of bibliographic sources is provided so that scholars might more readily obtain access to information omitted from the paper. The discussion also considers Washburn's professional life and personal characteristics and how she might be viewed as a role model.
"Nothing in the world is so compelling to the emotions as the mind of another human being" (Washburn, 1916b, p. 606). This statement, tucked away in an essay on the psychology of esthetic experience in music, provides an insightful clue to one of the motivations which sustained Margaret Floy Washburn's significant career as one of the most influential psychologists in psychology's first half–century as a distinct discipline. She held a life long fascination with the minds of humans and animals and was convinced that experimental psychology provided the appropriate methodology for exploring the topic. She devoted her unflagging energy and outstanding ability to the newly evolving science throughout a 43–year career which covered the period 1894–1937.