Spotlights, Floodlights, and the Magic Number Zero: Simple Effects Tests in Moderated Regression

Journal of Marketing Research, 2012, doi: 10.1509/jmr.12.0420

57 Pages Posted: 28 Jan 2013

See all articles by Stephen A. Spiller

Stephen A. Spiller

University of California, Los Angeles (UCLA) - Anderson School of Management

Gavan J. Fitzsimons

Duke University - Fuqua School of Business

John G. Lynch

University of Colorado-Boulder, Leeds School of Business - Center for Research on Consumer Financial Decision Making

Gary McClelland

University of Colorado at Boulder - Department of Psychology

Date Written: November 15, 2012

Abstract

It is common for authors discovering a significant interaction of a measured variable X with a manipulated variable Z to examine simple effects of Z at different levels of X. These “spotlight” tests are often misunderstood even in the simplest cases, and it appears that consumer researchers are unsure how to extend them to more complex designs. We explain the general principles of spotlight tests, show that they rely on familiar regression techniques, and provide a tutorial showing how to apply these tests across an array of experimental designs. Rather than following the common practice of reporting spotlight tests at one standard deviation above and below the mean of X, we recommend that when X has focal values, researchers report spotlight tests at those focal values. When X does not have focal values, we recommend researchers report ranges of significance using a version of Johnson and Neyman’s (1936) test we call a “floodlight”.

Keywords: moderated regression, spotlight analysis, simple effects tests

Suggested Citation

Spiller, Stephen A. and Fitzsimons, Gavan J. and Lynch, John G. and McClelland, Gary, Spotlights, Floodlights, and the Magic Number Zero: Simple Effects Tests in Moderated Regression (November 15, 2012). Journal of Marketing Research, 2012, doi: 10.1509/jmr.12.0420. Available at SSRN: https://ssrn.com/abstract=2208103

Stephen A. Spiller (Contact Author)

University of California, Los Angeles (UCLA) - Anderson School of Management ( email )

110 Westwood Plaza
Los Angeles, CA 90095-1481
United States

Gavan J. Fitzsimons

Duke University - Fuqua School of Business ( email )

Box 90120
Durham, NC 27708-0120
United States

John G. Lynch

University of Colorado-Boulder, Leeds School of Business - Center for Research on Consumer Financial Decision Making ( email )

Leeds School of Business
Boulder, CO 80309-0419
United States
919-971-5201 (Phone)

HOME PAGE: http://https://www.colorado.edu/business/john-g-lynch-jr

Gary McClelland

University of Colorado at Boulder - Department of Psychology ( email )

Boulder, 80309
United States

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