Exploring Marketing Research William G. Zikmund,Chapter 11: Experimental Research,Copyright 2000 by Harcourt, Inc. All rights reserved.,Experiment,A research investigation in which conditions are controlled One independent variable is manipulated (sometimes more than one) Its effect on a dependent variable is measured To test a hypothesis,Copyright 2000 by Harcourt, Inc. All rights reserved.,Manipulation of the Independent Variable Selection of Dependent Variable Assignment of Subjects (or other Test Units) Control Over Extraneous Variables,Basic Issues of Experimental Design,Copyright 2000 by Harcourt, Inc. All rights reserved.,Experiment Treatment,Alternative manipulations of the independent variable being investigated,Copyright 2000 by Harcourt, Inc. All rights reserved.,Independent Variable,The experimenter controls independent variable. The variables value can be manipulated by the experimenters to whatever they wish it to be.,Copyright 2000 by Harcourt, Inc. All rights reserved.,Manipulation of Independent Variable,Classificatory vs. Continuous Variables Experimental and Control Groups Treatment Levels More Than One Independent Variable,Copyright 2000 by Harcourt, Inc. All rights reserved.,Dependent Variable,Its value is expected to be dependent on the experimenters manipulation Criterion or standard by which the results are judged,Copyright 2000 by Harcourt, Inc. All rights reserved.,TEST UNITS - subjects or entities whose response to the experimental treatment are measured or observed.,Copyright 2000 by Harcourt, Inc. All rights reserved.,Controlling Extraneous Variables,Elimination of Extraneous Variables Constancy of Conditions Order of Presentation Blinding Random Assignment,Copyright 2000 by Harcourt, Inc. All rights reserved.,How May an Experimenter control for Extraneous Variation?,Eliminate Extraneous Variables Hold Conditions Constant Randomization Matching Subjects,Copyright 2000 by Harcourt, Inc. All rights reserved.,Demand Characteristics,Experimental procedures that intentionally hint to subjects something about the experimenters hypothesis,Laboratory Experiment,Field Experiment,Artificial-Low Realism,Few Extraneous Variables,High control,Low Cost,Short Duration,Subjects Aware of Participation,Natural-High Realism,Many Extraneous Variables,Low control,High Cost,Long Duration,Subjects Unaware of Participation,Copyright 2000 by Harcourt, Inc. All rights reserved.,Copyright 2000 by Harcourt, Inc. All rights reserved.,Control Groups,Isolates Extraneous Variation,Copyright 2000 by Harcourt, Inc. All rights reserved.,When does an Experiment have Internal Validity?,Internal Validity - The ability of an experiment to answer the question whether the experimental treatment was the sole cause of changes in a dependent variable Did the manipulation do what it was supposed to do?,Copyright 2000 by Harcourt, Inc. All rights reserved.,Factors Influencing Internal Validity,History Maturation Testing Instrumentation Selection Mortality,Copyright 2000 by Harcourt, Inc. All rights reserved.,Isolating Extraneous Variation with a Control Group,History Effects Maturation Effects Mortality Effects,Copyright 2000 by Harcourt, Inc. All rights reserved.,Increasing Internal Validity,Control Group Random Assignment Pretesting and Posttesting Posttest Only,Copyright 2000 by Harcourt, Inc. All rights reserved.,Quasi-Experimental Designs,One Shot Design (After Only) One Group Pretest-Posttest Static Group Design,Copyright 2000 by Harcourt, Inc. All rights reserved.,One Shot Design (After Only) X O1,Copyright 2000 by Harcourt, Inc. All rights reserved.,One Group Pretest-Posttest O1 X O2,Copyright 2000 by Harcourt, Inc. All rights reserved.,Static Group Design Experimental Group X O1 Control Group O2,Copyright 2000 by Harcourt, Inc. All rights reserved.,Three Good Experimental Designs,Pretest - Posttest Control Group Design Posttest Only Control Group Solomon Four Group Design,Copyright 2000 by Harcourt, Inc. All rights reserved.,Pretest-Posttest Control Group Design,Experimental Group R O1 X O2 Control Group R O3 X O4,Copyright 2000 by Harcourt, Inc. All rights reserved.,Posttest Only Control Group,Experimental Group R X O1 Control Group R O2,