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Understanding Research Design: Variables, Hypotheses & Validity

Explore research design essentials, including variables, hypotheses, internal and external validity, and experimental design. Learn to define scope, identify threats to validity, and consider qualitative designs for comprehensive analysis. Enhance your understanding of the research process and its applications.

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Understanding Research Design: Variables, Hypotheses & Validity

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  1. Research Design RCPT 436 Research & Technology Applications

  2. Units of Analysis • Individuals: students, participants, patients • Groups: classes, families, gangs • Organizations: universities, churches, recreation departments • Social Artifacts: books, paintings, songs, editorials, buildings

  3. A word of warning… • On average, students from Springfield score higher on the SATs then students from Shelbyville. What can we conclude about Lisa Simpson? NOTHING! An Ecological Fallacy results when you make conclusions about individuals based upon aggregate data.

  4. Variables • Definition: discrete phenomenon that can be observed in at least two mutually-exclusive categories • Dependent variable • Independent variables • Intervening variables

  5. Dependent Variable Independent Variable Intervening Variable Watching a Snickers Commercial Buying a Snickers from Vending Machine Hunger

  6. What other (independent) variables could explain our purchase of a Snickers?

  7. Defining the scope • Purpose statement • Significance statement • Theory or conceptual roadmap

  8. Which Hypothesis is Which? • Hypothesis • Null hypothesis • Non-directional hypothesis • Alternative hypothesis • Men will perform better than women on standardized tests. • The average scores for men and women will be different. • There will be no statistical difference between test scores

  9. Internal Validity • Determine whether a given program is working, if it meets standards, or how it compares to other programs • Properly demonstrates a causal relationship between two variables

  10. External Validity • Ability to generalize findings to the “real world” or beyond the sample • Results should be reproducible across different experimental settings

  11. Threats to External Validity • Selection bias • Experimental settings • Testing • Multiple treatment interference • Inadequate operational definition • Hawthorne effect • Selection interacting with any extraneous variables

  12. Experimental Design • Random selection of sample • Pretest • Random assignment to experimental and control groups • Post-test

  13. Variations • Quasi-experimental design – study participants not randomly assigned to control or experimental group • Pre-experimental – no control group • Non-experimental – individuals are observed or surveyed

  14. Qualitative Designs • Ethnography: holistic understanding (participant observation) • Case study: in depth study of a single phenomenon (visionary) • Content analysis: written, visual, or recorded documents (profanity on TV) • Historical study: studying the past (primary or secondary data; be skeptical) • Rigor determined by truthfulness, applicability, and consistency

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