Question

Each of the following scenarios describes a correlation between two variables. State whether the correlation is most likely due to a coincidence, a common underlying cause, or a direct cause. If there is an underlying cause, state what you think it is. If you believe that one variable directly causes the other, suggest possible physical causation.

1. Sales of winter boots are positively correlated with the sale of sidewalk salt.

2. I’ve noticed that the more hours I work each week, the more “Happy Meals” toys (from McDonald’s Restaurants) we collect at home.

3. A Kindergarten teacher noted that the amount of money he spends on art supplies each year is positively correlated with the amount he spends buying snacks for the class.

4. If I remember to bring my umbrella to work it doesn’t rain, but if I forget it at home it does. Sigh.

5. A large company notices that since it changed to more flexible hours, its absentee rate has fallen dramatically.

6. My neighbor the roofer hates when it rains. He says that the more days it rains, the less he earns a year.

7. The day on which we begin daylight savings time each fall was recently changed from mid-fall to early November and candy companies nationwide reported higher than usual sales in October.

8. People who drive red cars get caught speeding more often than those who drive other color cars.

9. Augsburg’s women’s hockey team wins more games when the three captains play.

10. The divorce rate in Maine is closely correlated to the per capita consumption of margarine in the United States. (This is actually a strong positive correlation.)

Answer 1

1. During winter, side walk salt is used for cleansing the snow/ice on the pathways. So in presence of sidewalk salt, the shoes of the people gets ruined faster than in the normal scenario. This ultimately leads to increase in the requirement of more shoes, and hence sales increases.

So Winter increases the sales of side walk salt which increases the sales of shoes.

Here , it is a direct relation.

4. Forgetting the umbrella has no relation with he rain. It is just coincidence.

5. Changing to flexible hours, encourages the employees to work as per their timings or availability. So, instead of taking holidays or not going to office they can reschedule their timings and can go to office when as per their convenience.

So flexible timings are directly related falling of absentee rate.

8. Within the visible range of light, red light waves are scattered the least by atmospheric gas molecules.

So red cars can be spotted easily than other color. Hence, red cars get caught speeding more often than those who drive other color cars.

So it is directly related.