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In this case, because pancreatic cancer is relatively rare, the impressive-sounding 50% reduction doesn't amount to very much. According to the American Cancer Society, a 60-year-old man has a 0.41% (1 in 241) chance of developing pancreatic cancer during the next ten years. (Risk varies greatly with age and is much lower at younger ages.) So cutting that risk in half might bring it down to about 0.2% (1 in 480). It's a 50% drop, sure, but the risk was already very small to begin with. In this case, it's more helpful to news and health care consumers to describe it as a 0.2 percentage point reduction. And then there are the harms of regular aspirin use; the Yale news release that the tweet links to doesn't mention any. But taking aspirin regularly isn't a harmless intervention - far from it. It's well known that taking aspirin every day can cause serious bleeding in the gastrointestinal system and, less frequently, in the brain. That's why guidelines for aspirin use in cardiovascular disease prevention don't recommend it for people at low risk of a heart attack. The potential benefits may be outweighed by the risks of a serious bleed.

Many public conversations we have about science-related issues involve communicating risks: describing them, comparing them and trying to inspire action to avoid or mitigate them. Just think about the ongoing stream of news and commentary on health, alternative energy, food security and climate change. Good risk communication points out where we are doing hazardous things. It helps us better navigate crises. It also allows us to pre-empt and avoid danger and destruction. But poor risk communication does the opposite. It creates confusion, helplessness and, worst of all, pushes us to actively work against each other even when it's against our best interests to do so. So what's happening when risk communications go wrong?

You may have heard the advice for pregnant women to avoid eating soft cheeses. This is because soft cheeses can sometimes carry the Listeria monocytogenes bacteria, which can cause a mild infection. In some cases, the infection can be serious, even fatal, for the unborn child. However, the infection is very rare, affecting only around 65 people out of 23.5 million in Australia in 2014. That's 0.0003% of the population. Of these, only around 10% are pregnant women. Of these, only 20% of infections prove fatal to the foetus. We're getting down to some very small numbers here. If we talked about every risk factor in our lives the way health authorities talk about soft cheeses, we'd likely don a helmet and kneepads every morning after we get out of bed. And we'd certainly never drive a car. The upshot of this example is to emphasise that our intuitions about risk are often out of step with the actualities. So journalists need to take great care when reporting risk so as not to exacerbate our intuitive deficits as a species.

Where else have you seen risk claims like "x causes 50% increase in health-problem y"? Do you tend to trust these claims? Do you understand what they mean? Would they change your behaviour? "Interpreting health (or any other) risk estimates reported in the media is not straightforward. Even health professionals can get tripped up trying to make sense of these statistics, so it is no wonder the public can easily be confused or misled. Often there is tendency to overreact to risk estimates, so it's worth unpacking what these really mean."

Interesting discussion of how we perceive risk, and the risks of everyday activities! So let's answer the first question: how likely is a fatal shark attack for an Australian? To get a crude estimate of this, averaged across the whole population, you would divide the number of people who have died due to a shark attack each year (on average three to four each year based on recent data) by the population of Australia (approximately 24 million). This yields a risk of approximately one in eight million per year, which is thankfully very low. Does this assuage your fear? If not, the reason is probably that the imagery of a shark attack is so terrifying. Any unusual and dramatic event has a huge impact on our psyche and this distorts our perception. Also, it's not that easy for us to interpret what a risk expressed as a relative frequency truly means.

Excellent discussion of absolute and relative risk in the context of alcohol safety. "But claiming there is no 'safe' level does not seem an argument for abstention. There is no safe level of driving, but government do not recommend that people avoid driving."

how could two groups of 'experts' come up with such different conclusions, given they broadly agree of the evidence? David Aaronovitch in the Times identified the critical underlying issue behind the ensuing conflict: whether we take an individual- or a population-based approach. Essentially, the authors point out that any absolute risks are small from an individual perspective, and may generally be cancelled out by the enjoyment of eating, and the bother of changing habits. But these small benefits can be important from a public-health, population-wide perspective, since a lot of people making a small change, that only reduces their risk by a personally-negligible amount, can add up to thousands fewer cases of disease. That's what has generated the disagreement. It can be perfectly reasonable for guidance to be given by authorities, and it can also be perfectly reasonable for individuals to ignore it. Both can be 'right'.

Medicine's decades-long march toward patient autonomy means patients are often now asked to make the hard decisions - to weigh trade-offs, to grapple with how their values suggest one path over another. This is particularly true when medical science doesn't offer a clear answer: Doctors encourage patients to decide where evidence is weak, while making strong recommendations when evidence is robust. But should we be doing the opposite?People in general are not great at evaluating risk. They worry more about shark attacks than car crashes.

It's not just disadvantaged and vulnerable groups that struggle with financial decision-making. People who are highly educated in finance also make poor decisions - for instance, by focusing too much on growing their assets and ignoring risks. But studies show that when regulation is effective and the financial system can be trusted, even consumers with limited financial knowledge and information-processing capabilities have the potential to deal with complex financial decisions. For example, when considering mortgage protection insurance, applicants stand to benefit from knowing the actual risk of events like serious illness or injury that can affect their ability to meet monthly loan repayments.

The more serious problem with California's law is one of effect size. Health, and cancer, aren't binary. Consumers can't just be concerned with whether a danger exists; they also need to be concerned about the magnitude of that risk. Even if there's a statistically significant risk between huge quantities of coffee and some cancer (and that's not proven), it's very, very small. Cigarettes have a clear and easily measured negative impact on people's health. Acrylamide, especially the acrylamide in coffee, isn't even close. Warning labels should be applied when a danger is clear, a danger is large and a danger is avoidable. It's not clear that, with respect to acrylamide, any of these criteria are met. It's certainly not the case regarding coffee. Whatever the intentions of Proposition 65, this latest development could do more harm than good.

An opinion piece in last week's Annals of Internal Medicine argues that just how aggressively we screen for some cancers can actually distort our understanding of the risk factors for a particular cancer, as well as how common we perceive it to be.

The benefits and harms of medical marijuana can be debated, but more states are legalizing pot, even for recreational use. A new evaluation of marijuana's risks is overdue. Last year, the National Academies of Sciences, Medicine and Engineering released a comprehensive report on cannabis use. At almost 400 pages long, it reviewed both potential benefits and harms. Let's focus on the harms.

Statistics is a useful tool for understanding the patterns in the world around us. But our intuition often lets us down when it comes to interpreting those patterns. In this series we look at some of the common mistakes we make and how to avoid them when thinking about statistics, probability and risk.

How excited would you be about a medication that lowered your risk of cardiovascular death, heart attack or stroke by 1.5%? Excited enough to spend a few thousand dollars a year on the drug? I expect not. What if, instead, the drug reduced those same terrible outcomes by 20%? That's probably enough benefit to interest some in the drug. Well, those statistics come from the same clinical trial, evaluating the same drug. In fact, they present the exact same results, but they simply do it in different ways.

Today's Examine dives into the maths. We'll look at the best estimates on catching and being injured by COVID-19, the chances of being harmed by the AstraZeneca vaccine, and the other broader risks and benefits. Hopefully, at the end of this, you are armed to make a better decision.

Discusses a recent paper and press-release (a short summary circulated to the media by the people involved. In research, this is generally a summary of the paper often published by the university or organisation that has conducted the research). Do you think starting to eat nuts is likely to decrease your risk of heart disease? What other behaviours or characteristics do you think nut-eating might be associated with? Would any of them also be related to health factors?

"Fenofibrate may reduce heart disease risk in some patients with type 2 diabetes" The release goes on to suggest that among patients with type 2 diabetes who also had high levels of triglycerides and low levels of "good" cholesterol, the drug lowered the risk of cardiovascular events compared with placebo. Sounds like it might be time to ask your doctor about the benefits of fenofibrate, right? Before you schedule that appointment, you might want to consider this detail that wan't included in the news release: The findings of benefit came from a small group of patients within a larger study whose results had previously been reported. And that larger study, known as ACCORD, found no overall cardiovascular benefit among patients treated with fenofibrate.

almost all the stories I looked at emphasized that "1 in 10 pregnant women" with Zika gave birth to babies with birth defects.But how many actual women does the "1 in 10" figure represent? How many actual babies with birth defects?You have to wade far down into all of these stories to find the numbers, whereas NPR puts them right in its headline:51 Babies Born With Zika-Related Birth Defects In The U.S. Last YearThe fact that 1 in 10 women with Zika have babies with birth defects is accurate but not nearly as informative as it could be.And when communicating to a general audience, it's misleading to the point of scaremongering to make the "1 in 10" headline the take-home message from the study.

Almost one in four cancers detected in men were overdiagnosed in 2012, according to our new research, published today in the Medical Journal of Australia. In the same year, we found that approximately one in five cancers in women were overdiagnosed. Overdiagnosis is when a person is diagnosed with a "harmless" cancer that either never grows or grows very slowly. These cancers are sometimes called low or ultra-low-risk cancers and wouldn't have spread or caused any problems even if left untreated. Cancer overdiagnosis can result in people having unnecessary treatments, such as surgery, radiotherapy and hormone therapy. Being diagnosed with cancer and having cancer treatments can cause physical, psychological and financial harms.

As Omicron surges through the community, getting the right answer from a Rapid Antigen Test (RAT) is not as straightforward as reading one or two lines off the kit. RATs are a convenient diagnostic tool to detect COVID virus fragments in nasal secretions or saliva. They are designed to be self-administered and give an answer in minutes. Detecting infection early is critical to preventing spread and allowing persons at risk of severe disease to get timely access to close monitoring and new life-saving therapies. As governments plan to distribute tens of millions of RAT kits to schools and workplaces in coming weeks to help Australians work and study safely, it is important that we understand how to best use this diagnostic tool to reduce transmission and unnecessary disruptions to our lives and economy.