Presentation on theme: "Exploring Marketing Research William G. Zikmund"— Presentation transcript:
1Exploring Marketing Research William G. Zikmund Chapter 11:Experimental Research
2Experiment A research investigation in which conditions are controlled One independent variable is manipulated (sometimes more than one)Its effect on a dependent variable is measuredTo test a hypothesis
3Basic Issues of Experimental Design Manipulation of the Independent VariableSelection of Dependent VariableAssignment of Subjects (or other Test Units)Control Over Extraneous Variables
4The experimenter has some degree of control over the independent variable. The variable is independent because its value can be manipulated by the experimenter to whatever he or she wishes it to be.
5Experiment TreatmentAlternative manipulations of the independent variable being investigated
6Independent Variable The experimenter controls independent variable. The variable’s value can be manipulated by the experimenters to whatever they wish it to be.
7Manipulation of Independent Variable Classificatory vs. continuous variablesExperimental and control groupsTreatment levelsMore than one independent variable
8Experimental Treatments The alternative manipulations of the independent variable being investigated
9Dependent VariableIts value is expected to be dependent on the experimenter’s manipulationCriterion or standard by which the results are judged
22When 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 variableDid the manipulation do what it was supposed to do?
24Isolating Extraneous Variation with a Control Group History EffectsMaturation EffectsMortality Effects
25Type of Extraneous Variable ExampleHistory - Specific events in theenvironment between the Beforeand After measurement that arebeyond the experimenter’s controlMaturation - Subjects changeduring the course of the experimentTesting - The Before measure alertsor sensitizes subject to nature ofexperiment or second measure.A major employercloses its plant intest market areaSubjects becometiredQuestionnaireabout the traditionalrole of womentriggers enhancedawareness of womenin an experiment.
26Instrument - Changes in instrument result in response biasSelection - Sample selectionerror because of differentialselection comparison groupsMortality - Sample attrition; some subjects withdraw from experimentNew questions aboutwomen are interpreteddifferently from earlierquestions.Control group andexperimental group isself-selected groupbased on preference forsoft drinksSubjects in one groupof a hair dying studymarry rich widows andmove to Florida