Correlation & Causation - Pre Algebra
- Among children ages 5 to 12, shoe size and reading level are positively correlated. What is the lurking variable?
- Age. Older children tend to have both larger feet and higher reading levels.
- What kind of study can establish that one variable causes a change in another?
- A randomized controlled experiment, in which the researcher assigns the treatment at random.
- What type of correlation exists between the height of a burning candle and the time it has been burning?
- Negative correlation. As burning time increases, the candle's height decreases.
- Fires with more firefighters present tend to cause more damage. What is the better explanation than firefighters causing damage?
- Larger fires both require more firefighters and cause more damage; fire size is the lurking variable.
- What does it mean for two variables to have no correlation?
- There is no consistent tendency for one variable to increase or decrease as the other increases.
- What does the statement that correlation does not imply causation mean?
- Two variables that change together are not proven to have a cause-and-effect link. Something else may explain the pattern.
- What is a lurking (confounding) variable?
- A third variable that affects both variables being studied, which can create an association between them.
- Ice cream sales and the number of swimming accidents rise and fall together. What is the most likely lurking variable?
- Hot weather. Warm temperatures increase both ice cream sales and the number of people swimming.
- Hours of TV watched and test scores have a negative correlation. Which conclusion is justified: TV lowers scores, or students who watch more TV tend to score lower?
- Students who watch more TV tend to score lower. The correlation alone does not show that TV causes the lower scores.
- What does a positive correlation between two variables mean?
- As one variable increases, the other tends to increase as well.
- What does a negative correlation between two variables mean?
- As one variable increases, the other tends to decrease.