1. The extra point. The scatterplot shows five blue data points at the left. Not surprisingly, the correlation for these points is r = 0. Suppose one additional data point is added at one of the five positions suggested below in green. Match each point (a-e) with the correct new correlation from the list given.

2. What's the cause? A researcher gathering data for a pharmaceutical firm measures blood pressure and the per- centage of body fat for several adult males and finds a strong positive association. Describe three different possi- ble cause-and-effect relationships that might be present.

3. What's the effect? Published reports about violence in computer games have become a concern to developers and distributors of these games. One firm commissioned a study of violent behavior in elementary-school children. The researcher asked the children's parents how much time each child spent playing computer games and had their teachers rate each child's level of aggressiveness when playing with other children. The researcher found a moderately strong positive correlation between computer game time and aggressiveness score. But does this mean that playing computer games increases aggression in children? Describe three different possible cause-and-effect explana- tions for this relationship.