1. MA 102 Statistical Controversies Friday, March 22, 2002 Today: Chapter 15 More on Correlation Regression Causation Reading : None new Exercises: 15.1, 15.3, 15.5, 15.6, 15.7, 15.9, 15.11, 15.12, 15.23, 15.25, 15.27

2. Causation A strong relationship between two variables does not establish causation. They may both be a common response to the other variables, or there may be a confounding variable. To establish causation, if at all possible, do a randomized comparative experiment!

3. Examples of causation? Do numbers of TV sets in a society cause greater life expectancy there? Does high Body-mass index in mothers cause high BMI in their daughters? Does availability of handguns increase violent crime? Does cigarette smoking cause cancer?