Experimental Research

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

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

Classificatory Vs. Continuous Variables Experimental and Control Groups Treatment Levels More Than One Independent Variable Manipulation of Independent Variables

Experimental treatments are the alternative manipulations of the independent variable being investigated.

DEPENDENT VARIABLE Its value is expected to be dependent on the experimenter’s manipulation Criterion or standard by which the results are judged

Selection - e.g., sales volume, awareness, recall Measurement Dependent Variable

TEST UNITS - subjects or entities whose response to the experimental treatment are measured or observed.

Constant Error Random Errors Two Types of Experimental Error

Elimination of Extraneous Variables Constancy of Conditions Order of Presentation Blinding Random Assignment Controlling Extraneous Variables

DEMAND CHARACTERISTICS EXPERIMENTAL PROCEDURES THAT INTENTIONALLY HINT TO SUBJECTS SOMETHING ABOUT THE EXPERIMENTER’S HYPOTHESIS

Guinea Pigs Hawthorne Effect Demand Characteristics

Field vs. Laboratory Experiment

Laboratory ExperimentField 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

WHEN IS AN EXPERIMENT INTERNAL VALIDITY? INTERNAL VALIDITY – Confidence that the only cause of change in the dependent variable came because of a change in the independent variable. Did the manipulation do what it was supposed to do?

History Maturation Testing Instrumentation Selection Mortality Factors Influencing Internal Validity

Type of Extraneous Variable Example History - specific events in the Environment between the Before and After Measurement That Are beyond the Experimenter’s Control Maturation - subjects Change during the Course of the Experiment Testing - The Before Measure Alerts or Sensitizes Subject to Nature of Experiment or Second Measure. A Major Employer Closes Its Plant in Test Market Area Subjects Become Tired Questionnaire about the Traditional Role of Women Triggers Enhanced Awareness of Women in an Experiment.

Other Factors Example Instrument - Changes in Instrument Result in Response Bias Selection - Sample Selection Error Because of Differential Selection Comparison Groups Mortality - Sample Attrition; some Subjects Withdraw from Experiment New Questions about Women are Interpreted Differently from Earlier Questions. Control Group and Experimental Group Is Self-Selected Group Based on Preference for Soft Drinks Subjects in One Group of a Hair Dying Study Marry Rich Widows and move to Florida

HOW CAN INTERNAL VALIDITY BE INCREASE?

Control Group Random Assignment Pretesting and Posttesting Posttest Only Increasing Internal Validity

WHAT ARE THE DIFFERENT BASIC EXPERIMENTAL DESIGNS?

One Shot Design (After Only) One Group Pretest-Posttest Static Group Design Quasi-Experimental Designs

ONE SHOT DESIGN (AFTER ONLY) XO 1

One Group Pretest-Posttest O 1 X O 2

Static Group Design Experimental GroupX O 1 Control Group O 2

Pretest - Posttest Control Group Design Posttest Only Control Group Solomon Four Group Design Three Good Experimental Designs

Pretest-Posttest Control Group Design Experimental Group O 1 X O 2 Control Group O 3 O 4

Posttest Only Control Group Experimental Group RX O 1 Control Group R O 2

Solomon Four Group Design Experimental Group 1:R O 1 X O 2 Control Group 1:R O 3 O 4 Experimental Group 2:R X O 5 Control Group 2: R O 6

Chinese Food Study Traditional Choice Studies Choose one from several (e.g. One meal from three, or none of the above) Paid to participate, regardless of answers Incentive Choice Study Choose one from several, chance you will have to live with your choice Get $ - cost of a meal + meal

Chinese Food Study Pilot Study 41 Participants. Study conducted in BAB classroom. All choose some meals during regular choice task. 21 did not choose a meal, when they had to pay.

Chinese Food Study Actual Study 108 Participants. Study conducted in New China Town Restaurant. All but 8 choose a meal in final task. Data more informative, can predict better, when participants have to live with their choices.

Chinese Food Study

Chinese Food Study (Results)

TEST MARKETING EXPERIMENTAL PROCEDURE OPPORTUNITY TO TEST A NEW PRODUCT NEW MARKETING PLAN UNDER REALISTIC MARKET CONDITIONS MEASURE SALES OR PROFIT POTENTIAL.

SELECTING A TEST MARKET POPULATION SIZE DEMOGRAPHIC COMPOSITION LIFESTYLE CONSIDERATIONS COMPETITIVE SITUATION MEDIA SELF-CONTAINED TRADING AREA SECRECY

CONTROL METHOD OF TEST MARKETING SMALL CITY LOW CHANCE OF BEING DETECTED DISTRIBUTION IS FORCED (GUARANTEED)

ADVANCED EXPERIMENTAL DESIGNS ARE MORE COMPLEX COMPLETELY RANDOMIZED RANDOMIZED BLOCK DESIGN LATIN SQUARE FACTORIAL