Vitamins

Read the two articles on the question of whether vitamins are bad for you.

Problems

1. The Brodie article states that ``Smokers who took 20 milligrams of beta carotene each day developed 18 percent more lung cancers than those who were given vitamin E or a dummy pill.'' What does this mean? What additional information would you need to decide if this difference is significant?

2. In the original article (New England Journal of Medicine, 14 April 1994) you will find that during the study there were 876 newly diagnosed cases of lung cancer with 474 among those who were given beta carotene and 402 among those who were not. The study was designed in such a way that there was essentially a 50% chance that each subject would be given beta carotene.

   If beta carotene has no effect then it might be reasonable to assume that the number of deaths among those who took beta carotene can be compared to the number of heads in tossing a coin 876 times. What is the approximate probability of getting 474 or more heads when a fair coin is tossed 876 times? Is this consistent with the claim that the increase in incidence of lung cancer for those taking beta carotene is significant at the 95% level?

3. On the basis of this study, Laurie has quit taking beta carotene. Was this a wise decision?