Experimental Designs 0 = measurement of dependent variable x = manipulation of independent variable R = random assignment of subjects E = change in dependent variable due to independent variable

After-only X O 1

One Group, Before-After O 1 X O 2

Before-After with Control Group Experimental Group (R) O 1 X O 2 Control Group (R) O 3 O 4

After-Only with Control Group Experimental Group (R) X O 1 Control Group (R) O 2

Test Marketing Experiment (or other type of study) conducted in a field setting

Test Markets zStandard

Test Markets zControlled

Test Markets zElectronic

Test Markets zSimulated

Selecting Test Market Cities Representativeness Ideal city is one where demographic and psychological characteristics most closely match desired population

Selecting Test Market Cities Degree of Isolation Distribution and promotion should be limited to one geographic area

Selecting Test Market Cities Ability to Control Distribution and Promotion Distributors and media sources need to be willing and able to cooperate

Internal Validity Extent to which change in Dependent variable is due to manipulation of independent variable

Threats to Internal Validity History/Extraneous Factors Specific events in the external environment occurring between first and second measurements that are beyond the control of the experimenter

Threats to Internal Validity Maturation/Changes in subjects Subjects change in some way over the course of the experiment

Threats to Internal Validity Testing Initial measurement affects test-taking the second time test is administered

Threats to Internal Validity Instrumentation/Measure Error Change in method of measuring dependent variable or change in degree of sensitivity or accuracy in measurement instrument

Threats to Internal Validity Mortality/Drop-Out Withdrawal of subjects from experiment before completion of experiment