Quantitative Research

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Quantitative Research
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Experimental Research Categories

• Randomized Experimental
• Use of comparison groups
• Random assignments to groups
• Quasi-experimental
• Manipulates treatments but doesnt use randomly
  assigned treatment groups
• Used when randomization of groups is impossible
• Typically has a pretest and posttest
• Pre-experimental
• No comparison group
• No pretest/weak design

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Internal Validity

• Indicates the extent to which the study is free
  of extraneous or confounding variables or factors
  that might account for results.
• i.e., could effects be due to enthusiastic
  teacher rather than the program under
  investigation?

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Threats to Internal Validity (p.61)

• Extraneous events
• Selection
• Maturation
• Subject attrition
• Pretesting (testing)
• Statistical regression
• Diffusion of treatment
• Experimenter effects
• Treatment fidelity
• Subject effects
• Instrumentation

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Criteria for Evaluating

• Is purpose clear? Significant?
• Review of LitCurrent? Organized?
• Is hypothesis/question(s) clearly stated?
• Is method of sampling clear?
• What was manipulated as independent variable(s)
• Are procedures for collecting data described
  fully?
• Are there any threats to internal validity?
• Do conclusions/interpretations follow logically
  from the results?
• Are limitations indicated?
• Is experiment so contrived and artificial that
  the findings have little generalizability?

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Class Activity

• In your content groups, answer the questions (3,
  4, 7 9) on pp. 71-72
• Fill in the Credibility Scorecard on p. 73

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