

GO FIGURE

Different ways of seeing stats

Is eating a pork sausage a day bad for you? In his regular column, Michael Blastland puts claims this week that it causes heart disease and diabetes through the Go Figure risk-o-meter. Out of the frying pan into the dock? To be a sausage this week was to stand accused - yet again - of crimes against health. Pity the pork farmer. Most media coverage failed, again, to give us the information we needed

About three years ago, evidence appeared to suggest that sausages were associated with colorectal cancer; this week, it was coronary heart disease. Read the headlines and the British banger is a loaded gun. But how risky is it really? Most media coverage failed, again, to give us the information we needed. Time, once more, to dust off the Go Figure risk-o-meter, or should we say 'risk-o-meater', my editor asks? Click through the slide show to see how it works. BACK {current} of {total} NEXT Most of the news stories slip up by giving only one number, an abstract percentage, 20% or 42%, to represent the increased risk from eating sausages. It doesn't say what the ordinary risk is. But an increased risk of even 100% makes little difference if the ordinary risk is only one in a million. A rise from one in a million to two in a million won't bother anyone. But if the ordinary risk is one in two, then 100% more makes a huge difference. So "increased by 100%" is a very variable feast. From bacon to booze, risks often make headlines



How to understand risk in 13 clicks In this case, 20% can equal one person in every hundred, while 42% can equal 20 people. It all depends where you start. It's an argument familiar to Go Figure regulars. One day, perhaps, journalism will catch on. Maybe all stories about risk should be required to include the words "from", and "to" as in: "the risk rises from to " and to state these risks as the number of people at risk in every 100. Meanwhile, it helps to know that the ordinary or baseline risk of heart disease is high, while the baseline risk of colorectal cancer is rather lower. Multiply each of these by the relevant extra sausage risk and you get quite different results. So if the research on sausages and heart disease stands up, this makes an appreciable difference to the risks each of us faces. Vegetarians Bear in mind, though, that the figures are based on eating an extra sausage every day, and that a great many other things influence the risks of heart disease and diabetes, and that links between a food and a health hazard (or benefit) do not always indicate a direct cause. Assumptions: Baseline rates of lifetime risk of heart disease are taken from a study reported in the Lancet, here . They've had a bad week The risk of heart disease is also affected by other factors, described here . Baseline rates of lifetime diabetes risk are harder to find. There are published figures for the US and Australia, though the US figures might be affected by higher rates of obesity there. The US figures can be found here . Given uncertainty about their applicability to the UK, we have used a round third as a crude approximation of the probable UK numbers. Diabetes risk varies considerably according to many factors other than sausages. A guide to the risk factors is here . There is also a perplexing qualification. That one small study - and it was small, so might not be reliable - found that a group of vegetarians had more colorectal cancer than meat eaters. Below are a selection of your comments. As always co-relation not causation, plus some extrapolation. People who eat processed pork products have a higher incidence of x than people who do not. Do pork products cause x? Is there a linear relationship between increased pork and increased x? Or are the egg and chips that accompany the pork product contributing? Food scares are great cheap journalism, but seldom very helpful.

Dave Waters, Northampton Thank you for your explicit rendering of a valuable statistical lesson. Most apologists for the food industry slither by this rather subtle mathematical truth.

DanInTheApple, New York City, USA Lies, damn lies and statistics. Thank you for bringing the abuse of stats (often as much out of ignorance as out of intent) on the nutritional debate. You also mentioned the study sample size, critically important to the validity of the study, and should also be mentioned with the stats. I'm off to have a sausage.

Paul Beckett, London, UK Thank god there are journalists who want to educate rather than create headlines. In general moderate intake of most things is healthy. But drink too much water, and it is toxic. There is one postscript to this article, which is that if heart disease doesn't get you, something else will.

Chris, London As the item states; It depends on where you draw your statistical baseline as to whether you see the risk as negligable or significant. Don't want to rain on anyone's parade, but we all die - including those with the most cautious and healthy lifestyles. Take Jim Fix (invented jogging), who died of a heart attack in his late 30's. So why worry yourself into an early grave?

Duncan, Glenrothes An excellent piece. The reporting of medical research in the media is often very misleading. Perhaps stories should also mention somewhere that correlation doesn't always equal causation!

David Trueman, High Wycombe Given that sausage recipes vary from good quality ones that contain up to 80% non-recovered meat to the ones that are more rusk and fat with minimal meat content saying that the British banger is bad for you is scaremongering. Perhaps manufacturers could state the ratio of ingredients, including country of origin and leave the customer to choose. However the better quality sausages will be out of range of the average household.

Hazel, Erith, Kent Short of saying plutonium is the secret ingredient in the typical banger, nothing you report would turn me away from a plate of bangers and mash. 'Nuff said.

Paul Seauvan, Sausalito, CA USA "One small study...found that a group of vegetarians had more colorectal cancer than meat eaters" If I was a meat eater, I would go around saying exactly the same thing. Besides, it makes meat eaters feel all warm inside to say something negative about vegetarians, doesn't it?!?

Patricia, Kent, UK My mother in law has been eating sausages and bacon fried in lard all her life. She has lots of sugar in her tea, and has real butter dripping from her toast, and she's still going strong at almost 96 years old! I say eat what you enjoy and don't worry, as next week it's likely that the news will be that sausages are good for you and extend you life!

Nigel Dixon, Wakefield UK



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