Thought Provoking Questions:

What will the pattern for the spread of AIDS look like? Can we predict how many people will develop AIDS next year?

Preliminary Work:

• Go to <: http://www.cdc.gov/hiv/stats/hasrlink.htm> and find the number of people in the state assigned to you who had AIDS for each of the years from 1982 through 2001.
• Put the data into two lists on your TI83, one being the number of years since 1980 and the other being the number of AIDS cases. At this point use the data only until 1990.
• Do a scatter plot and see if the graph appears to be exponential in shape.
• Do an exponential regression and record the equation.
• Use your equation to predict the number of AIDS cases in 2001.
• Compare your answer with the data you found.
• Why do you think your number is close to (or NOT close to) the actual value?
• Now enter all the data points you have.
• Does the graph appear to be exponential?
• Do a logistic regression and record the equation.
• Use this equation to predict the number of AIDS cases in 2001.
• Is this number better?
• If the logistic fit is a good one for your data, there will be a line of the form y = constant which appears to be an asymptote for the curve. Determine that constant.

Link to Answer Key for Preliminary Work Questions

Link to Excel Sample Data and Graph