Contents

xivPrefaceoverview of scientific communication, as well as what we hope are helpfultips when preparing a research manuscript (see Chapter 13), in this editionof our textbook we more frequently refer students to the Publication Manualand APA website.• Finally, if there is anything that brings out the gray hair in authors of amethods textbook, it is the perennial questions regarding the melding ofstatistical analysis with methodology: How much “stat”? Where does itgo? These questions have taken on a new flavor given the recent debateover null hypothesis significance testing (NHST) (see Chapter 11 for a briefreview of the issues) and the recommended use of effect size measures andconfidence intervals by, among others, the APA Task Force on StatisticalInference (see Wilkinson & The Task Force on Statistical Inference, 1999).Use of these statistical tools to supplement or even replace NHST is growing,but slowly (Cumming et al., 2007; Fidler, Thomason, Cumming, Finch,& Leeman, 2004; Gigerenzer, Krauss, & Vitouch, 2004). Moreover, newstatistical measures are being presented, as is illustrated by the recentflurry of interest in “probability of replication,” or p rep(see Killeen, 2005).We mention this latest statistical innovation in Chapter 12 but awaitfurther discussion in the psychological literature before enlarging ourpresentation.In this edition we have reduced the presentation of statistical analyses by removingmany formulas and sample calculations, and have eliminated some ofthe statistical tables in the appendices. Most statistical analyses are done usingcomputer software programs that deliver exact probabilities for test outcomesand various statistical tables, including those for conducting power analyses,are found on various sites on the Web. The table of t values is important forconstruction of confidence intervals and we kept this table, along with the Ftable and the random numbers table; the latter is useful for class exercises andrandom groups experiments.We continue to try to meet three goals in our presentation of statistical analysis:(1) to provide an independent introduction to statistical analysis in Chapters11 and 12 that will give students the means (no pun intended) to analyzea research study (and serve as a review for those who might already have hadthis introduction); (2) to show how method and analysis are related (see alsoour discussion of various methods and associated “Stat Tips”); and (3) to helpstudents appreciate that there are many statistical tools available to them andthey should not rely on only one as they seek to confirm what their data tellthem (see our discussion of statistical issues throughout the text).Online Learning CenterThe ninth edition of Research Methods in Psychology is accompanied by studentand instructor supplements available at www.mhhe.com/shaughnessy9e.These resources, created by Shaughnessy, Zechmeister, and Zechmeister toaugment the text material, have been updated for the ninth edition by coauthorJeanne Zechmeister.