Chapter 2: Correlational Study

1. Determine if the correlation is positive or negative.
2. Draw a simple graph of the relationship.
3. For each statement, give two or more possible explanations.

Example:
"A study found there were more home burglaries when a lot of ice cream was sold."
1. Positive correlation between the number of burglaries and the amount of ice cream, i.e. both variables move in the same direction.
2. (graph) On the axis: low-high number of burglaries, and number of pounds/dollars of ice cream sold.
3. Possible explanations: ice cream makes you want to rob a house, robbing a house makes you hungry for ice cream, hot weather causes people to eat more ice cream AND to leave their windows open, making them susceptible to burglaries.

(Assume these statements are true.)

1. A study of married couples showed that the longer they had been married, the more similar their political viewpoints.

2. Dogs who stay a long time at the adoption shelter are less friendly than dogs who are adopted earlier.

3. A college professor found that the more class absences students have, the lower their grades tend to be.

4. It was found that grade-school children who made high scores on a vocabulary test also tended to make high scores on a test of physical strength.