A 2013 Gallup poll asked randomly selected U.S. adults whether they wanted to stay at their current body weight or change. One purpose was to investigate whether there was any difference between men and women with regard to this aspect. Of the 562 men surveyed, 242 wanted to stay at their current weight, whereas of the 477 women surveyed, 172 wanted to stay at their current weight.
a. Is this an experiment or an observational study? Explain how you are deciding.
b. Organize the data in an appropriate well-labeled 2 × 2 table.
c. Find the observed difference in the conditional proportion of those who wanted to stay at their current weight between men and women.
d. Give two possible explanations for the observed difference in conditional proportions as reported in part (c).