Week 14 & 15.
Multivariate and within-subjects designs.
Lecture notes
Typical designs assign subjects to one group (i.e., control or experimental) or the other. These are between-subjects designs. We will discuss different conditions when it is more informative for subjects to be in more than one condition, or to be measured more than once: "within subject" designs.
Understand the key forms of these designs:
- Own control
- Each participant is in both the control and experimental groups.
- Makes the contrast between conditions very clear & strong.
- Order of groups must be counterbalanced.
- .Reveral designs
- Test the hypothesis that a behavior is controlled by a specific temporary condition.
- Test it by imposing the condition (e.g., stress) on people, then withdrawing it, then imposing it again.
- Design: A - B - A / Impose - withdraw - Iimpose condition.
- Repeated measures and randomized block designs
- Multiple treatment conditions: each participant gets each treatment, similar to an "own control" design..
- Longitudinal / time sampling: each participant assessed over multiple time periods.
- Randomized block designs; Repeated measure combined with between-groups variable, e.g., an experimental group and a control group, each measured over time.
Lecture notes are here.
Readings
Chapter 11 & discussion of interpreting studies with multiple measured and unmeasured variables, and readings on interpreting “relative risk” statistics, and interpreting data about risks + benefits of mammography.
Discussion group Assignment
Hand in & discuss your paper
Your paper is due this week in discussion group. Bring it in and be ready to talk about how it went and what you learned.
1. How did you come to your topic? Why is it important? How can research help us better understand that topic?
2. What was your theory? What hypothetical constructs were you examining? What was your specific hypothesis? How did you test your hypothesis; did you conduct a true experiment or a quasi-experiment?
3. What did you find? Were the results of your experiment statistically significant? How do you know?
4. What were the limitations of your study in terms of internal validity and external validity? Were there any confounds? What other research would be useful on your topic?
You should also bring in review questions from the statistics and complex design lectures.
