1 / 15

Experimental Designs

Experimental Designs. Single IV Designs. The basic two-group design. Independent Variable. Condition 1. Condition 2. Single IV Designs. Independent groups Randomly assigned to groups Kasser and Sheldon (2000). Mortality salience. Music. Single IV Designs. Nonequivalent groups

monifa
Télécharger la présentation

Experimental Designs

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. Experimental Designs

  2. Single IV Designs • The basic two-group design Independent Variable Condition 1 Condition 2

  3. Single IV Designs • Independent groups • Randomly assigned to groups Kasser and Sheldon (2000) Mortality salience Music

  4. Single IV Designs • Nonequivalent groups • IV is a subject variable • Reduce nonequivalence as much as possible by matching on important dimensions McDonald & Flanagan (2004) Non-TBI TBI

  5. Single IV Designs • Correlated groups • Matched groups • Natural pairs Blagrove (1996) Sleep-deprived Non-sleep-deprived

  6. Single IV Designs • Within-subject design • Repeated measures Lee and Aronson (1974) Moving forward Moving backward

  7. Single IV Designs • Advantages of independent-groups designs • Simplicity • In some contexts, it is impossible to use correlated groups

  8. Single IV Designs • Advantages of independent-groups designs • Simplicity • In some contexts, it is impossible to use correlated groups • Advantages of correlated-groups designs • Control—we have greater certainty of equality • Statistical benefits

  9. Statistics in a Two-Groups Design • Conceptually, what are we testing in a two-groups design? • What’s the null hypothesis? • What’s the alternative hypothesis? • What test should be used?

  10. between-groups variability statistic = error variability Statistics in a Two-Groups Design • Two sources of variability in your data: • The IV, or between-groups variability • Error variability, or within-groups variability

  11. Observations in a study can be divided into two components: • Signal: The key variable—the construct you’re trying to measure • Noise: All random factors in the situation that make it harder to see the signal

  12. Observation Signal Noise

  13. Signal Noise • You want the signal to be high relative to the noise

  14. Signal between-groups variability statistic = error variability Noise Statistics in a Two-Groups Design • Two sources of variability in your data: • The IV, or between-groups variability • Error variability, or within-groups variability

More Related