Chapter 11, Problem 30E

21–34. What’s the design? Read each brief report of statistical research, and identify

  a) whether it was an observational study or an experiment.

If it was an observational study, identify (if possible)

  b) whether it was retrospective or prospective.

  c) the subjects studied and how they were selected.

  d) the parameter of interest.

  e) the nature and scope of the conclusion the study can reach.

If it was an experiment, identify (if possible)

  b) the subjects studied.

  c) the factor(s) in the experiment and the number of levels for each.

  d) the number of treatments.

  e) the response variable measured.

  f) the design (completely randomized, blocked, or matched).

  g) whether it was blind (or double-blind).

  h) the nature and scope of the conclusion the experiment can reach.

30. Some people who race greyhounds give the dogs large doses of vitamin C in the belief that the dogs will run faster. Investigators at the University of Florida tried three different diets in random order on each of five racing greyhounds. They were surprised to find that when the dogs ate high amounts of vitamin C they ran more slowly. (Science News, July 20, 2002)