A Study of Effect Sizes in Marketing Experiments

Roger Marshall, Nanyang University
Loi Soh Loi, Nanyang University
Na WoonBong, Kyunghee University
ABSTRACT - An investigation is undertaken to empirically document the reported effect sizes of experiments reported in four leading marketing journals from the period 1985 to 1995, following a previous study concerned with the prior decade (Peterson, Albaum & Beltramini, 1985). Using omega-squared (w2), Pearson’s coefficient (r) and Cohen’s index (d) as measures of effect size, the results of 269 experiments, yielding a total of 1,399 experimental effects, were analyzed for the proportion of variance explained. Average incidence of reported w2 values has increased from 14% to 25% of experiments since the prior decade, but are still somewhat low.
[ to cite ]:
Roger Marshall, Loi Soh Loi, and Na WoonBong (2004) ,"A Study of Effect Sizes in Marketing Experiments", in NA - Advances in Consumer Research Volume 31, eds. Barbara E. Kahn and Mary Frances Luce, Valdosta, GA : Association for Consumer Research, Pages: 514-520.