Research Methods Scenario: Correlation and Causation

Read the following segment of an article:
No, poor people don't eat the most fast food
By Jay L. Zagorsky and Patricia Smith, The Conversation
Updated 6:57 AM ET, Wed July 12, 2017 CNN

Eating fast food is frequently blamed for damaging our health.

As nutrition experts point out, it is not the healthiest type of meal since it is typically high in fat and salt. More widely, it's seen as a key factor in the growing obesity epidemic in the U.S. and throughout the world.

Because it's considered relatively inexpensive, there's an assumption that poor people eat more fast food than other socioeconomic groups -- which has convinced some local governments to try to limit their access.

Food journalist Mark Bittman sums up the sentiment succinctly:
"The 'fact' that junk food is cheaper than real food has become a reflexive part of how we explain why so many Americans are overweight, particularly those with lower incomes."

Our recently published research examined this assumption by looking at who eats fast food using a large sample of random Americans. What we found surprised us: Poor people were actually less likely to eat fast food -- and do so less frequently -- than those in the middle class, and only a little more likely than the rich.

Original Source: Economics & Human Biology. Volume 27, Part A, November 2017, Pages 12–25

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  1. In this brief CNN article, they describe a correlation between two variables.
    What are the variables?




  1. Write an hypothesis that shows the correlation they found.


  1. How do you think they collected their data?


  1. Can they determine causation from this study? If yes, how? If no, why not?


  1. How many classes have you taken in which the scientific method (research method) was covered? Name them, if possible.