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# Ch12 2

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### Ch12 2

1. 1. Business Research Methods William G. Zikmund Chapter 12:Experimental Research
2. 2. Copyright © 2000 by Harcourt, Inc. All rights reserved. Requests forpermission to make copies of any part of the work should be mailed to the following address: PermissionsDepartment, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887-6777.
3. 3. 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
4. 4. Basic Issues of Experimental Design Manipulation of the Independent Variable Selection of Dependent VariableAssignment of Subjects (or other Test Units) Control Over Extraneous Variables Copyright © 2000 by Harcourt, Inc. All rights reserved
5. 5. The experimenter has some degreeof control over the independentvariable. The variable isindependent because its value canbe manipulated by the experimenterto whatever he or she wishes it tobe. Copyright © 2000 by Harcourt, Inc. All rights reserved
7. 7. Independent Variable• The experimenter controls independent variable.• The variable’s value can be manipulated by the experimenters to whatever they wish it to be. Copyright © 2000 by Harcourt, Inc. All rights reserved
10. 10. DEPENDENT VARIABLE• its value is expected to be dependent on the experimenter’s manipulation• criterion or standard by which the results are judged Copyright © 2000 by Harcourt, Inc. All rights reserved
13. 13. The dependent variable is socalled because its value isexpected to be dependent on theexperimenter’s manipulation; it isthe criterion or standard by whichthe results are judged. Copyright © 2000 by Harcourt, Inc. All rights reserved
24. 24. 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 Copyright © 2000 by Harcourt, Inc. All rights reserved
26. 26. WHEN IS AN EXPERIMENT INTERNAL VALIDITY?• INTERNAL VALIDITY - THE ABILITY OF AN EXPERIMENT TO ANSWER THE QUESTION OF 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
29. 29. 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 Copyright © 2000 by Harcourt, Inc. All rights reserved.
30. 30. Instrument - Changes in New Questions aboutInstrument Result in Response Women are InterpretedBias 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; Subjects in One Groupsome Subjects Withdraw from of a Hair Dying StudyExperiment Marry Rich Widows and move to Florida Copyright © 2000 by Harcourt, Inc. All rights reserved.
38. 38. 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
41. 41. One-Shot Design Internal Validity Problems• History • Instrumentation – weak – not relevant• Maturation • Selection – weak – weak• Testing • Mortality – not relevant – weak Copyright © 2000 by Harcourt, Inc. All rights reserved
42. 42. One-Group Pretest-Posttest Internal Validity Problems• History • Instrumentation – weak – weak• Maturation • Selection – weak – controlled• Testing • Mortality – weak – controlled Copyright © 2000 by Harcourt, Inc. All rights reserved
43. 43. Static-Group Design Internal Validity Problems• History • Instrumentation – controlled – controlled• Maturation • Selection – possible source of – weak concern • Mortality• Testing – weak – controlled Copyright © 2000 by Harcourt, Inc. All rights reserved
44. 44. Pretest-Posttest Control Internal Validity Problems• History • Instrumentation – controlled – controlled• Maturation • Selection – controlled – controlled• Testing • Mortality – controlled – controlled Copyright © 2000 by Harcourt, Inc. All rights reserved
46. 46. Posttest-Only Control Internal Validity Problems• History • Instrumentation – controlled – controlled• Maturation • Selection – controlled – controlled• Testing • Mortality – controlled – controlled Copyright © 2000 by Harcourt, Inc. All rights reserved
47. 47. Solomon four Group DesignExperimental Group 1: R O1 X O 2Control Group 1: R O3 O4Experimental Group 2: R X O5Control Group 2: R X O6 Copyright © 2000 by Harcourt, Inc. All rights reserved
49. 49. 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. Copyright © 2000 by Harcourt, Inc. All rights reserved
50. 50. Completely Randomized Designs Control: Experimental Experimental no music treatment: treatment: slow music fast musicAverage minutes 16 18 12shopper spendsin store Copyright © 2000 by Harcourt, Inc. All rights reserved
52. 52. Completely Randomized DesignWith a pretest posttest Group A R O1 X1 O2 Group A R O3 X2 O4 Group A R O5 X3 O6 Copyright © 2000 by Harcourt, Inc. All rights reserved
53. 53. Completely Randomized DesignWith a posttest Group A R X1 O1 Group B R X2 O2 Group C R X3 O3 Copyright © 2000 by Harcourt, Inc. All rights reserved
54. 54. 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. Copyright © 2000 by Harcourt, Inc. All rights reserved
56. 56. Factorial design• An experiment that investigates the interaction of two or more variables on a single dependent variable. Copyright © 2000 by Harcourt, Inc. All rights reserved
57. 57. Independent Variable 1 No Music Slow Music Fast MusicIndependent Variable 2 No Music cart signs Grocery cart signs Copyright © 2000 by Harcourt, Inc. All rights reserved
58. 58. Factorial Design -- Roller Skates Price Red Gold \$25 Cell 1 Cell 4 \$30 Cell 2 Cell 5 \$35 Cell 3 Cell 6Package Design Copyright © 2000 by Harcourt, Inc. All rights reserved
59. 59. 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. Copyright © 2000 by Harcourt, Inc. All rights reserved
62. 62. INDEPENDENT VARIABLE 1 Level 1 Level 2 Level 1 Group A Group BINDEPENDENT VARIABLE 2 Level 2 Group D Group C Copyright © 2000 by Harcourt, Inc. All rights reserved
63. 63. 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 Copyright © 2000 by Harcourt, Inc. All rights reserved
64. 64. 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 Copyright © 2000 by Harcourt, Inc. All rights reserved
65. 65. 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 Copyright © 2000 by Harcourt, Inc. All rights reserved
66. 66. 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. Copyright © 2000 by Harcourt, Inc. All rights reserved
67. 67. Order of UsageSUBJECT 1 2 3 1 A B C 2 B C A 3 C A B Copyright © 2000 by Harcourt, Inc. All rights reserved