title: Fractional factorial designs for legal psychology.
abstract: Researchers considering novel or exploratory psycholegal research are often able to easily generate a sizable list of independent variables (IVs) that might influence a measure of interest. Where the research question is novel and the literature is not developed, however, choosing from among a long list of potential variables those worthy of empirical investigation often presents a formidable task. Many researchers may feel compelled by legal psychology's heavy reliance on full-factorial designs to narrow the IVs under investigation to two or three in order to avoid an expensive and unwieldy design involving numerous high-order interactions. This article suggests that fractional factorial designs provide a reasonable alternative to full-factorial designs in such circumstances because they allow the psycholegal researcher to examine the main effects of a large number of factors while disregarding high-order interactions. An introduction to the logic of fractional factorial designs is provided and several examples from the social sciences are presented.
authors.affiliation: Litigation Department of Barnes & Thornburg, 11 South Meridian Street, Indianapolis, IN 46204, USA. dennis.stolle@btlaw.com
authors.forename: Dennis P
authors.initials: DP
authors.lastname: Stolle
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Robbennolt
authors.forename: Marc
authors.initials: M
authors.lastname: Patry
authors.forename: Steven D
authors.initials: SD
authors.lastname: Penrod
mesh_terms: D015986:Confounding Factors, Epidemiologic; D006801:Humans; D007603:Jurisprudence; D015999:Multivariate Analysis; D011584:Psychology / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012107:Research Design