Training our bullshit-o-meter

Murphy's Laws of Combat state that "The most dangerous thing in the world is a Second Lieutenant with a map and a compass." - compare here. Similarly, in the world of soft science, few is to be dreaded more than a writer with an agenda and colourful bullshitting skills. The tricky thing about bullshit is that it's difficult to distinguish from reasonable arguments - both may use some combination of words, graphs and numbers. There's nothing inherently bullshitty about those things, but like a map and a compass, you can do all kinds of stupid things with them.

I recently stumbled upon a fascinating little "infographic" about what seems to be the biggest menace to the western world since Hitler: sitting down! A certain degree of physical activity is healthy - that seems to be quite an agreeable theory. But the graphic conveys a warning to us that is way more radical:

 Wow! Now that's a scary message, especially since you're probably sitting on your chair or couch right now. So what is that figurative monster that lurks behind you while you are peacefully staring at your monitor? Let's try and follow the arguments that are presented in the graphic. So, how and why does sitting kill us?

According to the graphic, sitting increases risk of death. Risk of death is apparently defined as likelihood to die within 15 years. So, if you are sitting six hours or more per day, you are 40% more likely to die in the next 15 years than someone who sits less than 3.
So what's the bullshit here? Well, first of all, the graphic does not tell us who is compared with whom. The source doesn't tell us, it only indicates that the info is based on "modern Americans".
But the serious bullshit lies in making an assumption about causality from correlations. If we take a thousand people who sit a lot and compare them to a thousand people who don't like sitting, we might get a result similar to the one that is implied in the graphic: the sitters are more likely to die in the next fifteen years. So mortality rate and sitting habits correlate - there is a statistical connection between them. But that does not necessarily mean that sitting causes death, because correlation does not imply causality - as often, there is a good wikipedia article on that topic. There might be a common cause to death and sitting that explains at least some of the statistical connection. People who are chronically sick are both more likely to die and more likely to be physically unable to stand or walk around a lot. Older people in general - even those who are relatively healthy - might be more prone to sit, as they may be less required to be physically active because they retired from work or because they do not have children to keep them on their feet. Of course, older people are statistically more likely to die within the next fifteen years than the average. Conversely, toddlers and children are (thanks to modern medicine) very unlikely to die within fifteen years. Most of them also tend to be more physically active than adults. The graphic does not tell us that there may be common causes for sitting a lot and for a higher "death risk" - factors like age or health status. The causal connection between sitting and dying - meaning that the former causes the latter - is probably way less severe; most of the 40% - if that's even a reasonable number - are explained by a common cause, they merely present a correlation.

"Obese people sit for 2,5 more hours per day than thin people". That leaves us clueless: is sitting making people obese, or do obese people like to sit more than thinner people? Thankfully, the graphic spells it out: "Sitting makes us fat". It tells us that in twenty years, obesity doubled. Sitting time increased for 8%, while excercise rates stayed the same. This is probably meant to imply that a slight increase in sitting time causes a significant increase in obesity. But that's bullshit, again: Exercise rates and sitting time are not the only factors for obesity. Whether people with a realtively healthy metabolism gain or lose weight depends on how many energy they acquire by eating, and how many energy they spend. Both assumed causes of obesity are on the spending end; the graphic tells us nothing about how eating habits changed between 1980 and 2000. But without additional information about both eating habits and energy-spending habits, our knowledge base is too small to say anything of significance about the causes of obesity. I could as well tell you that, between 1980 and 2000, excercise rates stayed the same, while the number of nations that have won the fifa world cup increased by 17%, from 6 to 7. Obesity doubled. So obesity doubles whenever there is a first-time fifa world cup winner? Of course not - my litte example is obviously a correlation, and without additional data, there is no reason to consider tha graphic's information to be anything more than that. 

Now let's take a closer look to the graph on the bottom:

If we compare the length of the bars for "standing" and "walking", by counting the number of colums that they fill, we learn that the "% energy increase above sitting" of walking is 15 times higher than the energy increase of standing. That does not mean that walking burns fiften times as many calories as standing does. It only means that standing burns 10% more calories than sitting, while walking burns 150% more calories than sitting. If sitting burns 1 calorie per minute (as the graphic will states further below), standing burns 1,1 calories/m, while walking burns 2,5 calories per minute. That's not that much of a difference - but what we see is a very small bar next to "standing", and a comparatively huge bar next to "walking". That's bullshit at its best - there is no lying involved, and yet the reader is screwed over if he or she does not pay attention. If our bullshit-o-meter is not well-calibrated, we might fall for the graph and think that walking burns 15 times as many calories as standing does.


The artwork involved in the "infographic" is well-done. Just look at that nice dark dragon:

Even without reading the graphs and text, those shadowy demons and dragons make it clear to anyone: sitting is bad! Sitting is bad! While technically not bullshit, involving symbols of fear and death in the background of an "infographic" is at least quite manipulative, although I'd let them off the hook on that one, for the artistic effort. But there's one last piece of bullshit involved in the last "page": the good old historical argument:
"A hundred years ago, when we were all out toiling in the fields and factories, obesity was basically nonexistent". That may be true, but if you want to argue that sitting kills, while not sitting ("toiling in the fields" for example) is safe, you should keep your hands away from arguments like this. In 1900, life expectancy in the USA was 46,3 for men, 48,3 for women. In 1998, whe have numbers of 73,8 for men and 79,5 for women (source). Differences of life expectancy often seem more drastic because one of their main cause is infant mortality - a U.S. adult in 1900 could probably expect to live to at least 50 or 60 years of age. Still, while people in 1900 were thinner, they were not necessarily healthier - field and factory work without automated machinery and advanced farming equipment is hardly a healthy field of occupation. So I wonder, what exactly was the point in talking about how people lived a hundred years ago? The graph tells us that we have to "help our bodies in other ways" since "we can't exactly run free in the fields". But "the fields" were a place where most people used to plow and to pluck, not run around freely. The last page of the "infographic" confuses us with the notion that people used to be healthier when they worked in factories and fields, which is probably not a historical truth. With false assumptions like that, we cannot hope to gain anything but unproven conclusions - that's just bad soft science.

While the creators of the graphic certainly had good intentions, their argument contains correlations disguised as causality, confusing graphs, and false assumptions - or bullshit, if you will. But using our bullshit-o-meters, we can have a lot of fun with graphics like these, by turning their insults to our intelligence into a nice little training excercise for our soft science skills.