Class 13:  Monogamy

 

Discussion

An article in the New York Times reports an HIV infection rate for college students of 2 in 1,000. A 1992 study funded by the National Institute of Allergy and Infectious Diseases estimates the risk of heterosexual transmission of HIV from a single sexual encounter as follows:

Male-to-female transmission rate:

0.0005

 

 

Female-to-male transmission rate:

0.00005

(These estimates are for unprotected sex)

 

(For the following problems, you may choose the uninfected student to be of either gender)

If an uninfected student has a single encounter with a randomly selected student of the opposite sex, what is the probability that he/she will be infected with HIV?

If an uninfected student has 1 encounter each with 100 randomly selected students of the opposite sex, what is the probability that he/she will be infected with HIV?

If an uninfected student has 100 encounters with one randomly selected student of the opposite sex, what is the probability that he/she will be infected with HIV?

How do you explain these results?

Is the above procedure a reasonable way to estimate risk? If not, why not? If so, what are the implications?

 

Journal Assignment:

 

Read an article in the news that involves correlation.  A good way to find one is quickly is to go to the website of your favorite newspaper or magazine and search for the word “correlation”.  If you have trouble finding an article you like, or if you prefer, you can use the article Risky Business that is posted on Blackboard under Handouts -> Class 9. 

 

For whatever article you use, comment on the article and include answers to the following questions.   If you use your own article, please include a copy with your journal so that I can read it, too. 

 

1) What variables was the correlation between (e.g. height and weight, or temperature and crime rates, etc.)?  Which was thought of as the independent variable and which was the dependent variable? 

2) Was the correlation described in the article an ecological correlation or a correlation between values for individuals?

3) Was it a positive or negative correlation?  If mentioned, state the correlation coefficient. 

4) Discuss causation.  Does the article suggest that the independent variable caused the dependent variable to increase or decrease?   Is this plausible?  Do you agree?

5) Discuss strengths and weaknesses of the study.  Do you agree with its conclusions?  Why or why not?

 

Homework Assignment 9 for Tues, Sept. 29: 

On blackboard

 

Announcements

Journals due Tues Sept 29.  There are 4 journal assignments:  1) class survey data analysis, 2) SAT scores and family income plus picking colleges and drop-out rate, 3) correlation in meat consumption and height OR in another data set, 4) today’s assignment