Design of experiments with multiple independent variables: a resource management perspective on complete and reduced factorial designs.

Full Abstract

An investigator who plans to conduct an experiment with multiple independent variables must decide whether to use a complete or reduced factorial design. This article advocates a resource management perspective on making this decision, in which the investigator seeks a strategic balance between service to scientific objectives and economy. Considerations in making design decisions include whether research questions are framed as main effects or simple effects; whether and which effects are aliased (confounded) in a particular design; the number of experimental conditions that must be implemented in a particular design and the number of experimental subjects the design requires to maintain the desired level of statistical power; and the costs associated with implementing experimental conditions and obtaining experimental subjects. In this article 4 design options are compared: complete factorial, individual experiments, single factor, and fractional factorial. Complete and fractional factorial designs and single-factor designs are generally more economical than conducting individual experiments on each factor. Although relatively unfamiliar to behavioral scientists, fractional factorial designs merit serious consideration because of their economy and versatility.

Author information

Author/s: Collins, Linda M (LM); Dziak, John J (JJ); Li, Runze (R);

Affiliation: The Methodology Center, Department of Human Development and Family Studies, Pennsylvania State University, PA 16801, USA. lmcollins(-atsign-)psu.edu

Grants: K05 DA018206 (Agency:NIDA NIH HHS) ; P50 DA10075 (Agency:NIDA NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural

Journal: Psychological methods (Psychol Methods), published in United States. (Language: eng)

Reference: 2009-Sep; vol 14 (issue 3) : pp 202-24

Dates: Created 2009/09/01; Completed 2009/11/02;

PMID: 19719358, status: MEDLINE (last retrieval date: 11/2/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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