 CHAPTER 14
GENERALIZING RESULTS
 LEARNING OBJECTIVES
 Discuss the issues created by generalizing research results to other populations, including
potential problems using college students as research participants
 Discuss issues to consider regarding generalization of research results to other cultures and
ethnic groups
 LEARNING OBJECTIVES
 Describe the potential problem of generalizing to other experimenters, and suggest possible
solutions
 Discuss the importance of replications, distinguishing between exact replications and conceptual
replications
 Distinguish between narrative literature reviews and meta-analysis
 External Validity – Generalization Issues
Threats to External Validity
Population Validity
 Extent to which one can generalize from study sample to population
 Extent to which personological variables interact with treatment effects
 External Validity – Generalization Issues
Ecological Validity
1. Explicit description of experimental treatment
2. Multiple treatment interference
3. Hawthorne effect
4. Novelty and disruption effect
5. Experimenter effect
6. Pretest sensitization
7. Posttest sensitization
8. Interaction of history and treatment effect
9. Measurement of the dependent variable
10. Interaction of time of measurement and treatment
 GENERALIZING TO OTHER POPULATIONS
 Participants typically not selected from the general population
 College Students
 Volunteers
 Gender Considerations
 Locale
 Generalization as a Statistical Interaction
 In Defense of College Students and Rats
 CULTURAL CONSIDERATIONS
 Until recently experiments conducted with college students in the U.S. were primarily white,
which reflected college student population at the time
 Today most samples of college students are ethnically diverse, matching the more modern
diverse population in college
 CULTURAL CONSIDERATIONS
 Important to be aware of the ways in which the operational definitions of the constructs that we
study are grounded in a particular cultural meaning
 GENERALIZING TO OTHER EXPERIMENTERS
 The experimenter’s influence on subjects needs to be constant throughout the experiment
 Personality
 Gender
 Experience
 A solution is to use two or more experimenters
 PRETESTS AND GENERALIZATION
 Should a Pretest Be Given?
 Helps assess mortality effects
 There may be an interaction between the IV and the pretest variable
 REPLICATION AND GENERALIZATION
 Exact Replications
 An attempt to replicate precisely the procedures of a study
 Ascertain whether the same results are obtained with replication
 Conceptual Replications
 The use of different procedures to replicate a research finding
 The IV from previous study is manipulated in different ways
 EVALUATING GENERALIZATIONS
 Literature Review Provides Information that:
 Summarizes what has been found
 Tells the reader:
 What findings are strongly supported
 What findings are weakly supported
 Exposes inconsistent findings and areas lacking proper research
 Discusses future directions for research
 EVALUATING GENERALIZATIONS VIA LITERATURE REVIEWS AND META-ANALYSIS
 Meta-analysis: method for determining the reliability of a finding by examining the results from
many different studies
 Researcher combines actual results
 USING RESEARCH TO IMPROVE LIVES
 Goal of psychology is to promote human welfare
 Impact of psychological research
 Health
 Law and Criminal Justice
 Education
 Work Environments