Assignment One: Quiz on Friday Sept. 19th

Computer Part

A number of files are available to you in a public directory of my account on tuzo. You can see what they are by typing ls /student/jbrunner/public

Get a copy of the senic data for yourself by typing

cp /student/jbrunner/public/senic.dat .

Include the final period; it refers to your current directory.

Using pico (or some other unix text editor of your choice), delete all but the first 10 lines of the data file. At the top of the file, type your name and student number. Exit, save the file, and print it. You will be asked to hand this in with your quiz; it will be worth 3 points out of 10.

Conceptual Part

This will be based on the first 15 pages of the class notes (Part 1), and accompanying lecture. Re-read and think about the concepts. You might be asked to make up an original example of a study requiring a t-test, chi-square test of independence, one-way ANOVA or correlation. You could be asked what's the IV, the DV, and how to set up the data file. You could be given an example of one or more studies and asked to choose the appropriate test to answer the main research question. Here are some additional questions to think about.

  1. Make up an original example of a study that is multivariate, and both dependent variables are categorical.
  2. If p>.05, the results are significant and we can draw conclusions. True or False?
  3. In the example of cancer-prone mice on p. 7, how could the design be modified to allow comparison of 3 drugs and a placebo? Is this still repeated measures?
  4. On the same example, presumably the mice are so cancer-prone that they all come down with the disease eventually. But this might not happen, especially if one of the drugs is very effective. Explain how you would handle the data from a mouse that died of old age, and never showed signs of cancer.
  5. Is it possible to have a study with repeated measures and a categorical dependent variable? If it is possible, make up an original example. If it is impossible explainwhy.
  6. Is it possible for a study to be both experimental and observational? Explain.
  7. It is well known that people who graduate from university have higher lifetime earnings on average than those who do not. Explain the correlation-causation problem here. Design a study to resolve the issue.
  8. A useful non-parametric alternative to the two-sample t-test is the median test. Considering all the numerical values of the DV in one batch, recode the dependent variable as 0 = at or below the median, vs 1 = above the median. Then do a chisquare test of independence on the resulting 2 by 2 table. Explain how this method could be extended to provide an alternative to a one-way ANOVA for comparing 5 treatment means.

 

Note: In these questions, the word original is important. If you give an example that is overly similar to one in the class notes, your answer will receive a zero. If two people give the same example, they will both get a zero for the question.