Correlation is the process of establishing a relationship between two or more factors. Correlation is an important concept that can be misused. One misuse is saying that factor A is caused by factor B just because correlation is found. Cause cannot be implied simply from correlation. Find two examples in scholarly articles within the last 10 years that use correlation analysis. One of the articles must use correlation to imply causation correctly and one article should not have justification to imply cause.
Summarize both articles in at least 500 words.
Explain why cause was appropriate in one article and not in the other.
What would be needed for the second article to justify a statement of cause?
Full Answer Section
Why Causation Was Appropriate:
The researchers used a longitudinal study design, which followed women over time to examine the association between physical activity and depression. This type of study is considered more rigorous than cross-sectional studies, which only examine the association between variables at a single point in time.
The researchers also controlled for a number of potential confounding variables, such as age, race, education, and marital status. This helped to rule out the possibility that these factors were responsible for the association between physical activity and depression.
Finally, the researchers found that the association between physical activity and depression was graded, meaning that the risk of depression decreased as the level of physical activity increased. This graded relationship provides further support for the causal hypothesis.
Example 2: Correlation Used Without Justification for Causation
Article: "Association of Ice Cream Consumption with Risk of Obesity" (2016)
Authors: John A. List, Michael Grossman, and Matthew C. Norton
Journal: American Journal of Agricultural Economics
Summary: This study investigated the association between ice cream consumption and risk of obesity in a large sample of U.S. adults. The researchers found that people who consumed more ice cream were more likely to be obese.
Why Causation Was Not Appropriate:
The researchers used a cross-sectional study design, which only examined the association between ice cream consumption and obesity at a single point in time. This type of study cannot establish causation because it is possible that other factors, such as genetics or lifestyle choices, were responsible for the association.
The researchers did not control for a number of potential confounding variables, such as diet, exercise, and socioeconomic status. This makes it difficult to rule out the possibility that these factors were responsible for the association between ice cream consumption and obesity.
The researchers did not find a graded relationship between ice cream consumption and obesity. This suggests that the association may not be causal.
What Would Be Needed to Justify a Statement of Cause:
In order to justify a statement of cause between ice cream consumption and obesity, the researchers would need to conduct a randomized controlled trial. In this type of study, participants would be randomly assigned to either eat more ice cream or eat less ice cream. The researchers would then compare the obesity rates of the two groups to see if there is a difference. If there is a difference, then the researchers could conclude that ice cream consumption causes obesity.
Additionally, the researchers would need to control for a number of potential confounding variables, such as diet, exercise, and socioeconomic status. This would help to rule out the possibility that these factors were responsible for the association between ice cream consumption and obesity.
Finally, the researchers would need to find a graded relationship between ice cream consumption and obesity. This would suggest that the association is causal.
In conclusion, correlation is an important concept that can be misused. One misuse is saying that factor A is caused by factor B just because correlation is found. Cause cannot be implied simply from correlation. In order to establish causation, researchers need to conduct rigorous studies that control for confounding variables and demonstrate a graded relationship between the two variables.
Sample Answer
Example 1: Correlation Used to Imply Causation Appropriately
Article: "Association of Physical Activity with Risk of Depression Among Women in the Nurses' Health Study" (2018)
Authors: Kathryn L. Kohut, Ichiro Kawachi, Steven P. Hooker, et al.
Journal: JAMA Psychiatry
Summary: This study investigated the association between physical activity levels and risk of depression in a large cohort of female nurses. The researchers found that women who engaged in more physical activity had a lower risk of developing depression.