PU525 Unit 7 Relative Risk Headline Reflection Example

Eighteen Percent of What? A Seminar Reflection on a Headline Saying Processed Meat Raises Colorectal Cancer Risk by 18 Percent, a Figure I Had Repeated to My Father, and What the Session Showed When the Relative Increase Met a Lifetime Risk Near Four Percent

[Student Name]

Purdue University Global

PU525: Biostatistics for Public Health

Unit 7 Seminar Reflection

[Instructor Name]

[Date]

The seminar and family details are composite; the evaluation and statistics cited are real, and classmates are credited by role.

The Headline and My Mistake

The headline read: "Processed meat raises colon cancer risk by 18 percent." My father eats bacon most mornings, and I told him he was raising his cancer risk by almost a fifth. He stopped eating bacon for a week and then asked me what eighteen percent meant. I could not answer.

What the Seminar Showed

The figure comes from the 2015 evaluation by the World Health Organization's cancer research agency, which classified processed meat as a cause of colorectal cancer and estimated that each [50] grams eaten daily, about two slices of ham, increases risk by about [18] percent (Bouvard et al., 2015). That is a relative increase: eighteen percent more than the baseline risk, not eighteen percentage points. The baseline matters. Lifetime risk of colorectal cancer in the United States is roughly [4] percent, about one person in twenty-five (Siegel et al., 2023). An [18] percent relative increase raises that to about [4.7] percent, an absolute increase of about [0.7] percentage points, or roughly [7] more cases for every [1,000] people who eat that much processed meat every day for life. Eighteen percent sounded like a fifth of my father's life at stake; it was closer to seven people in a thousand.

Why the Two Framings Feel So Different

Relative risks sound larger than absolute ones, and research shows that patients and clinicians alike judge risks more accurately when given absolute numbers or natural frequencies (Gigerenzer et al., 2007). The headline was accurate but incomplete; a reader needed the baseline to understand it.

The Exercise That Changed My Ranking

Our instructor opened by projecting three headlines from the same week, each reporting a relative change without a baseline, and asked us to rank them by how worried we should be. Most of us ranked the processed meat headline highest. Then the instructor gave us the baseline risks and asked us to convert each to an absolute change per thousand people. The ranking reversed: a headline reporting a fifty percent rise in a very rare condition turned out to matter far less than our arithmetic for a common one, and the processed meat figure landed in the middle. Doing the conversion ourselves, rather than being told the answer, was what made the lesson stick.

Talking to My Father Again

After the seminar I called my father and walked him through the numbers. He asked whether two slices of ham counted as the fifty grams, and whether bacon on weekends only would count. I did not know, and I told him so. We agreed that cutting back was reasonable, that it was not an emergency, and that his blood pressure and his smoking history mattered more for his health than his breakfast. The conversation was better than the first one because it was honest about size.

What the Mistake Taught Me About My Future Work

As a public health professional, I will often be the person who translates a study for a family member, a community meeting or a reporter. If I could misread a headline in a way that frightened my own father, I can do the same at a larger scale.

What Classmates Argued

One classmate argued that the absolute framing could mislead in the other direction: seven in a thousand sounds small to an individual, yet across a whole population it adds up to many cases, and a small relative risk applied to a common exposure matters for public health. Another pointed out that the agency's classification describes how certain the evidence is that processed meat causes cancer, not how large the risk is, which is why it shared a category with tobacco despite a much smaller effect. Both points changed how I understood the story.

Where I Ended

The advice to eat less processed meat is sound, and for a population the benefit is real. For my father, the honest message is that eating it daily raises his lifetime risk from about four in a hundred to a little under five in a hundred. He can weigh that against how much he enjoys his breakfast. I owed him that version, not the headline.

What I Will Ask Before Repeating a Percentage

Eighteen percent of what? Is it a relative or absolute change? What is the baseline risk? Over what period? For how much exposure? Those five questions would have turned the headline into something my father could use.

A Question I Still Have

When a public health agency writes its own press release, should it lead with the relative figure, which reflects the strength of evidence for a cause, or the absolute figure, which reflects what an individual faces? The session did not settle that, and I am not sure it can be settled for every audience.

References

Bouvard, V., Loomis, D., Guyton, K. Z., Grosse, Y., Ghissassi, F. E., Benbrahim-Tallaa, L., Guha, N., Mattock, H., & Straif, K. (2015). Carcinogenicity of consumption of red and processed meat. The Lancet Oncology, 16(16), 1599-1600. https://doi.org/10.1016/S1470-2045(15)00444-1

Gigerenzer, G., Gaissmaier, W., Kurz-Milcke, E., Schwartz, L. M., & Woloshin, S. (2007). Helping doctors and patients make sense of health statistics. Psychological Science in the Public Interest, 8(2), 53-96. https://doi.org/10.1111/j.1539-6053.2008.00033.x

Siegel, R. L., Wagle, N. S., Cercek, A., Smith, R. A., & Jemal, A. (2023). Colorectal cancer statistics, 2023. CA: A Cancer Journal for Clinicians, 73(3), 233-254. https://doi.org/10.3322/caac.21772