Topic #2

It shows that the graph of the use of leaded gasoline between 1937 and 1986 is similarly shaped to a graph of violent crime between the years of 1960 and 2009. The authors of the article argue that this shape similarity could imply a causal relationship. Do you agree or disagree? What other factors might play a role in this relationship? Please remember to comment on at least one other student’s post.

Student Initial post #1

As we have heard so often throughout our program: "correlation does not equal causation." In this week's materials, we simply used the word "association" instead of "correlation." While association is defined as an "identifiable relationship between an exposure and disease," a cause only occurs when something actually makes the difference (Kim, 2023). As such, in order to determine if a situation involves a cause or is just an association, epidemiologists often ask: "Did the exposure cause the outcome?" (Kim, 2023).

The graph above shows that the use of leaded gasoline between 1937-1986 had a similar trajectory to the rate of violent crime between the years 1960 and 2009. While the authors of the article argue that this similarity could imply a causal relationship, it is more likely that the relationship is just an association. There are a variety of factors that could influence the similarity in the relationship. For example, the car industry began to really take off throughout the twentieth century, which could explain the increase in gasoline use. Additionally, given that Great Depression lasted until 1939, the graph shows a time in which many Americans may have been influenced to purchase a vehicle given that the economy was gradually improving. As for violent crimes, BBC remarks that "many violent crimes [during this period] emerged due to the rapid technological, social, and economic changes" (BBC, 2023). Additionally, increased rates of crime may have been simply a result of increased reporting. As such, given the variety of factors, it is unlikely that the use of leaded gasoline and violent crime in the twentieth century was a causal relationship.

Works Cited

BBC. (2023). The Growth of Crime in the 20th and 21st Centuries.

N.C. Government and Heritage Library. (2020, May 26). The Automobile: Social Game Changer. NCPedia. .

Edited by on Jan 17 at 1:06pm