What happens when someone you know is diagnosed with breast cancer? Does that kind of news make women more likely to get a mammogram themselves? The answer might surprise you.
NPR's Shankar Vedantam presents a study by two economists who had access to a unique dataset. In a company with thousands of employees, they analyzed anonymous health records of the 7000 female employees who were age 50 or older. Specifically, the researchers knew whether each employee had received a breast cancer diagnosis or not. And the knew whether, and when, each woman had scheduled a routine mammogram. What's more, they knew approximately where, in the company's buildings, each woman worked.
The economists studied the patterns of health behavior to test this question: when a coworker has breast cancer, is that associated with the women who work with her getting their own mammograms in the months that follow?
Journalist Vedantam reports a series of bivariate relationships from the study. Think about the two variables in each one, and sketch a graph of each. For example, the researcher is quoted saying this:
We find that on average when a woman is diagnosed with breast cancer, her co-workers – her immediate female coworkers – reduce their propensity to have a breast screening in the year in which the diagnosis takes place.
a) In this quote, what are the two measured variables? Is the first one quantitative or categorical? Is the second one quantitative or categorical? What kind of graph would you use to depict the result–a bar graph or a scatterplot? Sketch a graph of the results described above.
Are you surprised by what they found? The researchers say the pattern is consistent with a theory of "information aversion:"
…psychologists and social scientists talk about this idea of information aversion – the idea that maybe you don't want to find out about some really bad news because of the way it makes you feel.
Here's a description of another study:
the data not only showed which women were diagnosed, but how serious their cancer was. So oncologists would say the stage … of the cancer. And what the economists find is that the co-workers of the women with the most serious cancers are the most likely not to get screened…
b) in the description above what are the two measured variables? Is the first one quantitative or categorical? Is the second one quantitative or categorical? What kind of graph would you use to depict the result–a bar graph or a scatterplot? Sketch a graph of the results described above.
Doing well so far? Here's one more bivariate result from the study to practice on:
…the data showed where the women worked physically at the company literally – where they sat and how far they were from one another. And what the economists find is that co-workers who are physically closer to the patient also become less likely to screen.
c) in the description above, what are the two measured variables? Is the first one quantitative or categorical? Is the second one quantitative or categorical? What kind of graph would you use to depict the result–a bar graph or a scatterplot? Sketch a graph of the results described above.
d) Can we use these data to support the causal claim that the journalist used as the story's headline?: How A Co-Worker's Breast Cancer Diagnosis Affects Colleagues
Apply the three causal criteria to one of the three bivariate correlations you have sketched. Do the data and design support the causal claim?