Week 6.
Sampling
Lecture notes
This week we will finish with basic experimental design, and discuss sampling.
Key issues in gathering a research sample:
Who do you want to generalize to?- Who is the target population?
- broad
increases
external validity - Narrow increases internal validity
- broad
- How do you decide who is a member?
- demographic / behavioral criteria?
- subjective / attitudinal
- What do you know about the population already – what is the “sampling frame”.
- Is the population “Hidden” in some way?
- Socially undesirable research topic?
- Easily available via telephone, door-to-door?
- Targeted / multi-frame; sampling every niche of a population
- Respondent driven or “snowball”; sampling entire social networks (click image for interesting paper on romantic linkages among youth).
- quota sampling.
Lecture notes are here.
Readings
Chapters 7 & 10.
Readinngs: An article from the New York Times on the importance of context in interpreting results from large studies of mothers who work. A Tribune piece on Sampling, statistics, and interpreting school test scores. Finally, the image to the right shows the extensive screening that takes place for a drug trial of anti-depressants. Click for a journal article that asks whether participants in drug studies of anti-depressants are representative of depressed patients generally. The article can be a bit technical, but I will use it in lecture
Discussion group Assignment
Analyze a research design
For this assignment we want you to analyze a research study. For your paper you will cite at least two journal articles, at least one of which must be an empirical study, not a review or discussion paper. For discussion group this week take one of the empirical papers you will use for your paper and analyze it.
As a first step go to the Guide to Reading Journal Articles first. Then, answer the questions in the box in one typed page or so.
Participant Selection |
Participant Assignment |
Experimental Procedures |
Experimental Treatment or Manipulation |
Interpretation of Results |
Sample |
Group A |
Procedure
A |
Treatment |
Outcome |
Group B |
Procedure A |
No
treatment |
Outcome |
|
How did the researchers ensure
that the sample was representative
of the larger population? |
How were participants assigned to groups?...random assignment? matching? Did they ensure the groups started out exactly the same? Was there any self-selection or other bias? If there was bias, how should the groups have been assigned? |
How did they ensure equality
of procedures across groups -- what experimental controls
were present? |
What was the independent variable? Dependent variable? Were there any confounds of
the independent variable? |
Did the groups "really" differ
- was the difference statistically significant? What would it have meant if the groups were different, but: a) only by a very small amount, or; b) there was a confound? |
IIn case you cannot find an appropriate article for your paper, we have provided two articles, one on diary writing and the immune system and one on sunscreen use at the beach.
