**Class 15: HIV Vaccines**

**Discussion**

Read
the article ÒAIDS vaccine promising; experts urge cautionÓ from the San
Francisco Chronicle.

1)
The article says that the vaccine was Ò31%
effective in preventing HIV protection in comparison with placeboÓ. What does this mean? Where did the 31% figure from?

2) What does it mean that half the
participants given placebos?
Why was this done? If the
control group had not been given placebos, how do you think this would have
affected the results of the trial?

3) If the vaccine makes no difference, how many of the 125 cases
of new HIV infection would you expect in the vaccine group and how many in the
placebo group?

4) If you flip a coin 125 times, what is the
chance that you get exactly 74 heads?
What is the chance that you get at least 74 heads / how would you figure
this out? What does this have to
do with the HIV vaccine trial?

**Journal Assignment: **

Read the list of project
ideas and write down at least two project ideas that you would be interested in
doing. The ideas do not have to
come from the list.

**Homework Assignment for Tues,
Oct 20: **

On blackboard

**Announcements**

Since I cancelled the
birthday problem journal assignment, there have been only 3 journal assignments
so far: 1) Car and Goats, 2) Drug
testing, 3) Final project ideas. Please hand these in on Tuesday.