We live in a world where every week a new headline promises that a drug cuts your risk in half or slashes disease by a huge percentage. Sounds impressive. But those numbers often leave out context that actually matters for your real world health decisions. In public health we talk about absolute risk reduction and relative risk reduction. Headlines often only report the relative risk reduction (because it sounds better), but they should also report the absolute risk reduction.
I made a video in my kitchen with bouncy balls and a few household props to show why a “50 percent reduction” can sometimes mean something very different than you think. Absolute risk reduction tells you how many people are actually helped in the real world. Relative risk reduction tells you how big the reduction looks on paper. Both numbers come from the same data. They just tell very different stories.
But let me be VERY clear about what this video IS and what it ISN’T, because some folks got upset by it:
The example in this video was intentionally simplified to explain a statistical concept: the difference between relative risk reduction and absolute risk reduction, and why headlines often emphasize one over the other. Many people don’t understand these statistical concepts, so I tried to be as simple as possible (playground level simple.) This video IS a commentary on how risk is framed in mainstream health communication, and how that may influence one’s perception of a drug/intervention/supplement/whatever.
What this video is NOT:
I wasn’t making a claim about the population-level impact of a real drug. That’s a different question. For the purpose of this video, I’m talking about a fictious heart drug and a fictious trial. (Please let that sink in!) Population impact of a drug depends on baseline risk, uptake, comorbidities, adherence, duration of use, external validity, and real-world heterogeneity. This video is a teaching example about RISK FRAMING AND HEADLINES, not a clinical claim about the value of a specific drug or intervention.
Relative risk and absolute risk answer different questions, and both matter depending on the decision being made. In fact, many organizations dedicated to evidence-based science and medicine advocate for the reporting of both relative risk and absolute risk reduction. Population impact requires additional assumptions that weren’t part of my example in the video. However, if this explanation feels uncomfortable to you, it may be because we’re used to seeing relative risk presented without context. That’s exactly the communication gap this video was meant to highlight.
Sooo, if you want to understand health statistics in a way that is simple, visual, and actually fun, watch the video. If it helps you understand absolute risk and relative risk reduction better, I’ll have succeeded. If it encourages you to pause when you see a health headline or a percentage and read for more details, I’ll consider this a success. If your takehome point is that there is a story behind every number, I’ll consider that a win.
Watch on my Youtube Channel below. You can also watch on my Instagram Channel Here. :)
If this video resonated with you, watch my video on anecdotes here. Anecdotes are another area where everyone, willingly or unwillingly, misrepresents.
If you are strong on anecdotes, than watch my mortality rate vs case fatality rate video here. I use Bird Flu Headlines as a real-life example of how even seasoned health experts confuse the two and then go on TV and misinform the public.
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