Since August 2007, eleven detached feet have been found in the borderland of British Columbia, Canada, and Washington, United States. They had been disarticulated and no bodies have been found, despite the even more bizarre fact that all of them were wearing sneakers. Some of them even sported socks.

Asked by the press, experts called the series of discoveries “astounding” and “almost beyond explanation”. Unusual theories were brought to surface, ranging from a shipwreck or an airplane crash, from which the corpses have never been recovered, to the one claiming that the feet could have come from the 2004 Tsunami in the distant island of Indonesia. In fact, one of the feet was wearing a sneaker sold mainly in India, and almost all of the sneakers had been manufactured before 2004.

There was also the Hollywood inspired fear of a psychopath in action, one obsessed with cutting off feet in sneakers. The explanation, however, lies somewhere in the story of the crazy Statistician.

Abraham Wald was a peculiar Jewish mathematician born in Europe who migrated to the USA to escape from the Nazis. Wald applied his brains to a seemingly simple task: evaluating airplanes’ vulnerability. To do so, he observed the aircrafts full of holes that came back from the front. Quite simple, right? One should reinforce the more damaged patches to give them better chances of a successful return.

However, after elaborating sophisticated analysis techniques, his unique recommendation may sound insane. Wald suggested that the patches that had not been damaged were actually the most vulnerable, and they were the ones where armour should be added first. Something like wearing a band-aid where there is no wound. What for?

The answer is in the aircraft he analysed – they were the ones that had actually returned from the front. Wald’s insight was taking took into consideration that the airplanes that had returned were the ones that had made it through all the misadventures. The holes were a tell-tale sign of the strongest spots, the ones which could resist the mishaps, not the weakest areas. It was the other way round: the pristine spots pinpointed the places that could not be hit, otherwise the planes would have been lost in combat and would never be analysed by him back at home. The ones that did return with intact weakest areas had been lucky.

Wald’s analysis considered what is called selection bias: the data set has already been selected somehow, and a proper analysis must consider that. Here is another example: have you ever wondered why the line is never busy when when you call a wrong number?

Actually, we only realize we dialled the wrong number when someone on the other end answers the phone. We keep on our minds a very peculiar data selection. If the call is left unanswered, we hear the busy line tone without ever realizing we dialled the wrong number. An appalling mystery arises if we do not take into account that the data we are considering has been selected already by some process.

Which brings us back to the severed feet mystery. The solution to this conundrum does not involve any huge accident, nor any Tsunami dragging feet along for millions of miles away, and thankfully it doesn’t involve an electric saw psychopath either.

The simple answer is that the feet belong to people that committed suicide jumping into the waters nearby the area. Those that could be identified were linked to depressed individuals who had been reported as missing. There was no sign whatsoever that the limbs had been separated with the use of any tool. On the contrary, those extremities detaches as part of the natural body decay process and the most recent foot found was still connected to the leg bones.

But why were all of them wearing sneakers? It cannot be just by accident, and indeed it wasn’t. The truth is, sneakers are designed to be light, and so they usually float in water. The suicide victims who wear heavier shoes end up having their feet sunk to the bottom of the waters, despite being separated from the rest of the body. On the other hand, the ones who were wearing sneakers had their feet floating for a while until some of them reached the coast. The one to blame for picking the feet in sneakers is not a psychopath; it is the natural water buoyancy.

Exactly like the hit airplanes, exactly like the busy line, the cut off feet mystery is the result of a peculiar and a rather morbid selection bias. It could sound quite depressing, because it means there are many more feet out there to be found that belonged to suicidal people. Those who wear shoes will hardly ever be found.

In order not to end it on such a dark remark, it is worth pinpointing that even this article displays a biased selection. Only a story with a title that draws attention end up getting a post that you, dear curious reader, have followed so far. It worked, didn’t it? Since you are reading this far, since you have been selected, I can assure you I know it did. Like all the other news, it is easier to sell tragic stories, but that does not mean that the world is a more and more terrifying place.

There is a whole lot of good news, of small gestures of kindness that will never show up on the breaking news. Any analysis, even if not quite rigorously statistical, must take those into account, and I hope that getting to know what selection bias is and its importance helps you face things in a different way. [via Marginal Revolution, BoingBoing]

© forgetomori 2012. | Permalink

“The Paulding Light also known as "The Dog Meadow Lights" have been a mystery in Upper Michigan for over 40 years. To this day you can see them on almost any night!”

And they are not faked.

The first recorded sighting of the Paulding Light came in 1966 when a group of teenagers reported the light to a local sheriff. Since then, the mysterious light appears nearly every night at the site.

Although stories of the light vary, the most popular legend involves the death of a railroad brakeman. The legend states that the valley once contained railroad tracks and the light is the lantern of the brakeman who was killed while attempting to stop an oncoming train from colliding with railway cars stopped on the tracks.

The fact there never were railroad tracks there is but a small detail. Those could be ghost railroads, you know.

Fact is, the Paulding Light Mystery can be quickly solved by looking at it with a telescope. As these students from Michigan Technological University lead by Jeremy Bos show:

They are car headlights from US-45, of which a stretch about 5 miles away lines up at the exact location.

If you view the original video again, you can actually see that the brighter white lights are inbound car headlights on the left lane, with a high beam which is then dimmed for approaching traffic on the opposite direction… of which you can then see the red tail lights!

How could this be a mystery for 40 years, one may ask? Well, it wasn’t. As Bos point out, another team had investigated the site in the 1980s and reached the same conclusion. Several people realized the same even before that.

But like the more widely known Marfa Lights, which by the way have the same explanation, legend and mystery spread faster and longer than prosaic explanations.

© forgetomori 2011. | Permalink

Here’s a 32 year-old Carl Sagan speaking about flying saucers.

Fascinating bit of history. In that same year, the young astronomer published the book “Intelligent Life in the Universe”, along with Soviet Iosef Shklovskii. In that book, a scientific collaboration during the Cold War, Sagan and his Soviet fellow would delve and speculate into questions that unfortunately have not changed very much half a century later.

This is both because they were visionaries – the ubiquity of exoplanets was by no means a given in the 1960s, much to the contrary – and also because we still have not made contact nor found any conclusive evidence of intelligent life elsewhere in the Universe. Sadly.

This book is also very notable because, even before one Swiss guy exploited the idea, Sagan and Shklovskii analyzed seriously the idea of gods as ancient astronauts. Even a famous Sumerian tablet with several planets is discussed, decades before another alleged “expert” made a lot of fuss about it.

Now, back to the video interview, the man besides Sagan is also very notable, and not only because of the eypatch (due to an automobile accident) or the fact he lights up a smoking pipe. He’s Thornton Page, a noted astronomer and previously part of the Robertson panel on UFOs. Most importantly, along with the same Carl Sagan, he would promote a UFO symposium on the American Association for the Advancement of Science.

That’s right, in 1969, one of the most representative institutions of science, the one that actually publishes Science, held a symposium about UFOs. Paul E. McCarthy has a very interesting dissertation on the backstage of this episode of UFO, and science, history: Politicking and Paradigm Shifting: James E. McDonald and the UFO case study. [hattip to Leonardo Stern]

© forgetomori 2011. | Permalink

Lovely work from Ninjerktsu, click for the full comic, complete with apple pies.

© forgetomori 2011. | Permalink

Experience 3D without the fuss of cumbersome glasses! According to an experiment by Jonathan Post presented by one Francois, all you have to do is stick some small gadgets to the side of your head, activate them with two remote controls and have your eyes electrocuted so that they blink frenetically in synchrony with the images in a display.

This is such a great prank, and it definitely is a prank – even if the system was real, no one would seriously propose such a thing, not even for “CES 2012”.

But is the system real, that is, did they manage to have someone blink that fast?

You may remember one of the pioneers of face electrocution on the web, Japanese artist Daito Manabe. On the video above he tries to reproduce the feat with his equipment, without success.

“With my device, muscle couldn’t move faster over 9Hz”, he writes. “Also it was impossible to open my eyes when blinking was too fast.”

Note that in the video description, Jonathan Post claims his device only works on 120Hz displays! Surely no one can blink 120 times per second. The eyes would just shut. Twitching your eyes and actually having them fully shut and open are different things.

Even assuming he had his eyes blinking at a fraction of that speed (60, 30, 15 Hz…), we would also have to wonder how he managed to electrically stimulate his eyelids with such tiny wireless devices, which besides strobing lights also happen to be synchronized with very polished remote controls. Controls that must be sending infrared signals – he points the RCs to the tiny things – so besides strobing lights and electrocuting your face, those tiny, tiny things are also supposed to have infrared sensors.

One could speculate that perhaps on the right spot and the right voltages, one could stimulate not only the eyelids to shut, as Manabe did, but also to open, and then one would be able to blink faster. But then, when you see the video, he simply puts the tiny things in the side of his head without much care of exactly where he was putting it.

This works too well and is too polished a thing for a “prototype”. But is exactly what you would expect if you wanted to simulate you had some gadgets electrocuting your eyelids. The remote controls are more appropriated for an air conditioner, the 120Hz value is probably a number he got from actual 3D display technologies.

I bet that the video was instead created with CGI. He is not actually blinking that fast.

So far the only thing we know from Jonathan Post is the video itself, and very soon he will reveal what he was actually promoting. More than a couple million views in three days… well deserved, as this is one more of those virals that make you laugh and then think.

Something short of an Ig Nobel.

© forgetomori 2011. | Permalink