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14-1. 14-2 McGraw-Hill/Irwin © 2003 The McGraw-Hill Companies, Inc.,All Rights Reserved. Part Three SOURCES AND COLLECTION OF DATA.

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Presentation on theme: "14-1. 14-2 McGraw-Hill/Irwin © 2003 The McGraw-Hill Companies, Inc.,All Rights Reserved. Part Three SOURCES AND COLLECTION OF DATA."— Presentation transcript:

1 14-1

2 14-2 McGraw-Hill/Irwin © 2003 The McGraw-Hill Companies, Inc.,All Rights Reserved. Part Three SOURCES AND COLLECTION OF DATA

3 14-3 Chapter Fourteen EXPERIMENTATION

4 14-4 Variables in Experiments Independent variables Dependent variables

5 14-5 Advantages of an Experiment? Researchers ability to manipulate the independent variable Contamination from extraneous variables can be controlled more efficiently Convenience Cost Replication

6 14-6 Disadvantages of Experiments Artificiality of the laboratory Generalization from nonprobability samples Larger budgets needed Restricted to problems of the present or immediate future Ethical limits to manipulation of people

7 14-7 Experimentation Process Select relevant variables Specify the treatment levels Control the experimental environment Choose the experimental design Select and assign the participants Pilot-test, revise, and test Analyze the data

8 14-8 Ways to Assign Subjects Random Assignment Matching Assignment –Quota matrix

9 14-9 Does a Measure Accomplish What it Claims? Internal validity External validity

10 14-10 Threats to Internal Validity History Maturation Testing Instrumentation Selection Statistical Regression Experimental Mortality

11 14-11 Threats to External Validity The Reactivity of Testing on X Interaction of Selection and X Other Biasing Effects on X –Artificial setting of testing –Respondents knowledge of testing

12 14-12 Experimental Designs Preexperimental designs True experimental designs Field experiments

13 14-13 Design Symbols X the introduction of an experimental stimulus to the participant 0 a measure or observation activity R an indication that sample units have been randomly assigned

14 14-14 Preexperimental Designs One-shot case study One-group pretest-posttest design Static group comparison

15 14-15 True Experimental Designs Pretest-posttest control group design Posttest-only control group design

16 14-16 Operational Extensions of True Designs Completely randomized designs Randomized block design Latin square Factorial design Covariance analysis

17 14-17 Field Experiments: Quasi- or Semi-Experiments Non Equivalent Control Group Design Separate Sample Pretest-Posttest Design Group Time Series Design


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