Research Methods William G. Zikmund, Ch12


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Research Methods
William G. Zikmund

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Research Methods William G. Zikmund, Ch12

  1. 1. BusinessResearch Methods William G. Zikmund Chapter 12:Experimental Research
  2. 2. 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
  3. 3. Basic Issues of Experimental Design• Manipulation of the Independent Variable• Selection of Dependent Variable• Assignment of Subjects (or other Test Units)• Control Over Extraneous Variables
  4. 4. The experimenter has some degree ofcontrol over the independent variable.The variable is independent because itsvalue can be manipulated by theexperimenter to whatever he or shewishes it to be.
  5. 5. Experiment TreatmentAlternative manipulations of the independent variable being investigated
  6. 6. Independent Variable• The experimenter controls independent variable.• The variable’s value can be manipulated by the experimenters to whatever they wish it to be.
  7. 7. Manipulation of Independent Variable• Classificatory Vs. continuous variables• Experimental and control groups• Treatment levels• More than one independent variable
  8. 8. Experimental Treatments• The alternative manipulations of the independent variable being investigated
  9. 9. Dependent Variable• Its value is expected to be dependent on the experimenter’s manipulation• Criterion or standard by which the results are judged
  10. 10. Dependent Variable• Selection – e.g... sales volume, awareness, recall,• Measurement
  11. 11. Test Units• Subjects or entities whose response to the experimental treatment are measured or observed.
  12. 12. Two Types of Experimental Error• Constant errors• Random errors
  13. 13. Field versusLaboratory Experiments
  14. 14. Controlling Extraneous Variables• Elimination of extraneous variables• Constancy of conditions• Order of presentation• Blinding• Random assignment
  15. 15. How May an Experimenter control for Extraneous Variation?• Eliminate Extraneous Variables• Hold Conditions Constant• Randomization• Matching Subjects
  16. 16. Establishing Control
  17. 17. Demand Characteristics• Experimental procedures that intentionally hint to subjects something about the experimenter’s hypothesis
  18. 18. Demand Characteristics• Guinea pig effect• Hawthorne effect
  19. 19. Field Vs. Laboratory Experiment
  20. 20. Laboratory Experiment Field Experiment Artificial-Low Realism Natural-High Realism Few Extraneous Many Extraneous Variables Variables High control Low control Low Cost High Cost Short Duration Long Duration Subjects Aware of Subjects Unaware of Participation Participation
  21. 21. Control GroupsIsolateextraneousvariation
  22. 22. 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 variableDid the manipulation do what it was supposed to do?
  23. 23. Factors Influencing Internal Validity• History• Maturation• Testing• Instrumentation• Selection• Mortality
  24. 24. Isolating Extraneous Variation with a Control Group• History Effects• Maturation Effects• Mortality Effects
  25. 25. Type of Extraneous Variable ExampleHistory - Specific events in the A major employerenvironment between the Before closes its plant inand After measurement that are test market areabeyond the experimenter’s controlMaturation - Subjects change Subjects becomeduring the course of the experiment tiredTesting - The Before measure alerts Questionnaireor sensitizes subject to nature of about the traditionalexperiment or second measure. role of women triggers enhanced awareness of women in an experiment.
  26. 26. Instrument - Changes in New questions aboutinstrument result in response bias women are interpreted differently from earlier questions.Selection - Sample selection Control group anderror because of differential experimental group isselection comparison groups self-selected group based on preference for soft drinksMortality - Sample attrition; some Subjects in one groupsubjects withdraw from experiment of a hair dying study marry rich widows and move to Florida
  27. 27. How can Internal Validity Increase?
  28. 28. Increasing Internal Validity • Control group • Random assignment • Pretesting and posttesting • Posttest only
  29. 29. What are the Different Basic Experimental Designs?
  30. 30. Quasi-Experimental Designs• One Shot Design (After Only)• One Group Pretest-Posttest• Static Group Design
  31. 31. One Shot Design (After Only) X O1
  32. 32. One Group Pretest-Posttest O1 X O2
  33. 33. Static Group DesignExperimental Group X O1Control Group O2
  34. 34. Three Good Experimental Designs • Pretest - Posttest Control Group Design • Posttest Only Control Group • Solomon Four Group Design
  35. 35. Pretest-Posttest Control Group DesignExperimental Group R O1 X O 2Control Group R O3 X O 4
  36. 36. Posttest Only Control GroupExperimental Group R X O1Control Group R O2
  37. 37. One-Shot DesignInternal Validity Problems• History • Instrumentation – weak – not relevant• Maturation • Selection – weak – weak• Testing • Mortality – not relevant – weak
  38. 38. One-Group Pretest-PosttestInternal Validity Problems• History • Instrumentation – weak – weak• Maturation • Selection – weak – controlled• Testing • Mortality – weak – controlled
  39. 39. Static-Group Design Internal Validity Problems• History • Instrumentation – controlled – controlled• Maturation • Selection – possible source of – weak concern • Mortality• Testing – weak – controlled
  40. 40. Pretest-Posttest ControlInternal Validity Problems• History • Instrumentation – controlled – controlled• Maturation • Selection – controlled – controlled• Testing • Mortality – controlled – controlled
  41. 41. Solomon Four-Group Design Internal Validity Problems • History • Instrumentation – controlled – controlled • Maturation • Selection – controlled – controlled • Testing • Mortality – controlled – controlled
  42. 42. Posttest-Only ControlInternal Validity Problems• History • Instrumentation – controlled – controlled• Maturation • Selection – controlled – controlled• Testing • Mortality – controlled – controlled
  43. 43. Solomon Four Group DesignExperimental Group 1: R O1 X O2Control Group 1: R O3 O4Experimental Group 2: R X O5Control Group 2: R X O6
  44. 44. Advanced Experimental Designs are More Complex• Completely randomized• Randomized block design• Latin square• Factorial
  45. 45. Completely Randomized Design• An experimental design that uses a random process to assign subjects (test units) and treatments to investigate the effects of only one independent variable.
  46. 46. Completely Randomized Designs Control: Experimental Experimental no music treatment: treatment: slow music fast musicAverage minutes 16 18 12shopper spendsin store
  47. 47. Independent Variable ALevel 1 Level 2 Level 3Group A Group B Group C
  48. 48. Completely Randomized DesignWith a pretest posttest Group A R O1 X1 O2 Group A R O3 X2 O4 Group A R O5 X3 O6
  49. 49. Completely Randomized DesignWith a posttest Group A R X1 O1 Group B R X2 O2 Group C R X3 O3
  50. 50. Randomized Block Design• An extension of the completely randomized design in which a single extraneous variable that might affect test units’ response to the treatment has been identified and the effects of this variable are isolated by blocking out its effects.
  51. 51. Randomized Block Design Independent Variables Control: Experimental Experimental no music treatment treatment: slow music fast musicBlocking variable Mornings and afternoons Evening hours
  52. 52. Factorial Design• An experiment that investigates the interaction of two or more variables on a single dependent variable.
  53. 53. Independent Variable 1 No Music Slow Music Fast MusicIndependent Variable 2 No Music cart signs Grocery cart signs
  54. 54. Factorial Design -- Roller Skates Package Design Price Red Gold $25 Cell 1 Cell 4 $30 Cell 2 Cell 5 $35 Cell 3 Cell 6
  55. 55. Effects• Main effect • Interaction effect• The influence of a • The influence on a single independent dependent variable by variable on a combinations of two dependent variable. or more independent variables.
  56. 56. 2 x 2 Factorial Design Ad A Ad B Men 65 Main Effects > of GenderWomen 65 70 60 > Main Effects of Ad
  57. 57. 100 Interaction Between Gender and Advertising Copy 90 Wo 80 me n 70Believability 60 Men 50 40 30 20 10 Ad A Ad B
  58. 58. Independent Variable 1 Level 1 Level 2 Level 1 Group A Group BIndependent Variable 2 Level 2 Group D Group C
  59. 59. 2 x 2 Factorial with a Pretest Posttest Group A R O1 X11 O2 Group B R O3 X21 O4 Group C R O5 X12 O6 Group D R O7 X22 O8
  60. 60. 2 x 2 Factorial Design with a Posttest Measure Group A R X11 O1 Group B R X21 O2 Group C R X12 O3 Group D R X22 O4
  61. 61. A Test Market Experiment on Pricing Sales in Units (thousands) Regular Price Reduced Price Cents-Off Coupon $.99 $.89 Regular PriceTest Market A, B, or C 130 145 153Test Market D, E, or F 118 143 129Test Market G, H, or I 87 120 96Test Market J, K, or L 84 131 99Mean X1=104.75 X2=134.75 X1=119.25Grand Mean X=119.58
  62. 62. Latin Square Design• A balanced, two-way classification scheme that attempts to control or block out the effect of two or more extraneous factors by restricting randomization with respect to the row and column effects.
  63. 63. Order of Usage 1 2 3 1 A B CSUBJECT 2 B C A 3 C A B
  64. 64. TEST MARKETING Not just trying But scientific something testing outControlled experimentation
  65. 65. Test Marketing Not just trying But scientific something testing outControlled experimentation
  66. 66. Test Marketing• An experimental procedure that provides an opportunity to test a new product or a new marketing plan under realistic market conditions to measure sales or profit potential.
  68. 68. A Lengthy and Costly Procedure When not $$$$$ to Test? Loss of How Long Secrecy Should a Test Last?
  69. 69. Popular Test Markets• Pittsfield, • Eau Claire,Wisconsin Massachusetts • Wichita, Kansas• Charlotte, North • Tulsa, Oklahoma Carolina • Omaha, Nebraska• Columbus, Ohio • Grand Junction.• Little Rock, Arkansas Colorado• Evansville, Indiana • Wichita Falls, Texas• Cedar Rapids, Iowa • Odessa-Midland, Texas
  70. 70. Selecting a Test Market• Population size• Demographic composition• Lifestyle considerations• Competitive situation• Media• Self-contained trading area• Overused markets - secrecy
  71. 71. Control Method of Test Marketing• Small city• Low chance of being detected• Distribution is forced (guaranteed)
  72. 72. The Advantages of Using the Control Method of Test Marketing• Reduced costs• Shorter time period needed for reading test market results• Increased secrecy from competitors• No distraction of company salespeople from regular product lines
  73. 73. Some Problems Estimating Sales Volume• Over-attention• Unrealistic store conditions• Reading competitive environment incorrectly• Incorrect volume forecasts – Adjusted data – Penetration and repeat purchase rate• Time lapse
  74. 74. High Tech Test MarketsElectric TestMarkets Simulated Test Markets Virtual-reality Simulated Test Markets