1 / 13

QUASI-EXPERIMENTS

QUASI-EXPERIMENTS. What is a Quasi-Experiment?. Compare subjects in different conditions on a DV Lacks one or more criteria for an experiment (cause, comparison, control) Interpreted like a correlational study . Why Do Quasi-Experiments?.

happy
Download Presentation

QUASI-EXPERIMENTS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. QUASI-EXPERIMENTS

  2. What is a Quasi-Experiment? • Compare subjects in different conditions on a DV • Lacks one or more criteria for an experiment (cause, comparison, control) • Interpreted like a correlational study

  3. Why Do Quasi-Experiments? • Internal validity is a problem because the IV is not manipulated • It may not be possible or ethical to manipulate the IV

  4. What is an Ex Post Facto Design? • Compare groups that differ on a pre-existing variable (subject variable) • Examples: • gender • personality • presence of mental disorder

  5. What is a Single-Group Posttest Only Design? • Scores are measured after a treatment for one group • The treatment is not manipulated, and there is no comparison

  6. What is a Single-Group Pretest-Posttest Design? • Scores are measured before and after an event or treatment • The treatment is not manipulated

  7. What is a Non-Equivalent Control Group Pretest/Posttest Design? • Compare a treatment group and a control group before and after the treatment • The groups are not randomly assigned

  8. What is a Single-Group Time Series Design? • Scores are measured several times before and after an event or treatment • Better than Pretest-Posttest design, because you can tell whether the change is likely to be due to a random fluctuation

  9. What is a Multiple-Group Time Series Design? • Scores for a treatment and control group are measured several times before and after • The control group is not randomly assigned • Combination of Nonequivalent Control Group and Interrupted Time Series

  10. What is a Cross-Sectional Design? • Compare different age groups at one point in time • The groups may differ on other variables, since age is not manipulated • cohort effects - generational history differences

  11. What is a Longitudinal Design? • Measure the same group at different ages • Time-consuming • Attrition can be a problem

  12. What is a Sequential or Cohort Design? • Compare different age groups at different ages • Combination of longitudinal and cross-sectional

  13. How Are Quasi-Experiments Analyzed? • Choose from the same set of statistics used for experiments • Remember that you interpret differences like the study was correlational • Take into account number of conditions and whether variables are between or within subjects

More Related