1 / 17

Chapter 9 Enhancing Rigor in Quantitative Research

Chapter 9 Enhancing Rigor in Quantitative Research. Controlling Extraneous Variables. Controlling external, situational factors—constancy of conditions. Constancy of the environment Constancy of treatment conditions Constancy of time Constancy of communications to subjects.

liana
Download Presentation

Chapter 9 Enhancing Rigor in Quantitative Research

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. Chapter 9Enhancing Rigor in Quantitative Research

  2. Controlling Extraneous Variables Controlling external, situational factors—constancy of conditions • Constancy of the environment • Constancy of treatment conditions • Constancy of time • Constancy of communications to subjects

  3. Controlling Intrinsic Subject Characteristics • Randomization • Repeated measures • Homogeneity • Blocking • Matching/balancing • Statistical control

  4. Principles of Analysis of Covariance—Schematic Diagram

  5. Benefits and Limitations of Control Methods: Randomization Benefits: • Controls all extraneous variables • Does not require advance knowledge of which variables to control Limitations: • Ethical and practical constraints on manipulation • Possible artificiality of conditions

  6. Benefits and Limitations of Control Methods: Repeated Measures Benefits: • If done with randomization, strongest possible approach • Reduces sample size requirements Limitations: • Cannot be used if there are possible carry-over effects from one condition to another

  7. Benefits and Limitations of Control Methods: Homogeneity Benefits: • Easy to achieve • Enhances interpretability of relationships Limitations: • Limits generalizability • Requires knowledge of which variables to control

  8. Benefits and Limitations of Control Methods: Blocking Benefits: • Enhances interpretability of relationships • Offers possibility of examining blocking variable as an independent variable Limitations: • Manageable only with a few blocking variables • Requires knowledge of which variables to control

  9. Benefits and Limitations of Control Methods: Matching Benefits: • Enhances interpretability of relationships • Easy to do if there is a large pool of available comparison group subjects Limitations: • Manageable only with a few matching variables • Requires knowledge of which variables to control • May be hard to find comparison group matches

  10. Benefits and Limitations of Control Methods: Statistical Control Benefits: • Enhances interpretability of relationships • Easy and economical • Can be used with a large number of extraneous variables Limitations: • Requires knowledge of which variables to control • Requires statistical sophistication

  11. Characteristics of Good Research Design in Quantitative Studies • Statistical conclusion validity • Internal validity • External validity • Construct validity

  12. Threats to Statistical Conclusion Validity • Low statistical power • Inadequate precision • Unreliable implementation of a treatment • Inadequate participation in treatment conditions

  13. Problems with Treatment Implementation: Analytic Options Analytic strategies when subjects withdraw from study or fail to get full exposure to treatment: • On protocol analysis • Intention to treat principle • Analysis of “dose” of treatment received

  14. Threats to Internal Validity • History • Selection • Maturation • Testing • Instrumentation • Mortality

  15. Table 9.2 Research Designs and Threats to Internal Validity

  16. Accessible vs. Target Population Accessible population: The population available for a particular study Target population:The total group of people in whom a researcher is interested and to whom results could be generalized

  17. Threats to External Validity • Inadequate sampling • Expectancy effects • Novelty effects • Interaction of history and treatment effects • Experimenter effects • Measurement effects

More Related