THE SURVIVOR BIAS

You must have heard stories about dolphins that save drowning people by pulling them out onto the shore. There are many such stories - so many that one could draw a conclusion that a special link exists between humans and dolphins. This is nonsense, of course, since the conclusion is made based only on the accounts of survivors - those saved by the dolphins. But nobody had ever polled those whom dophins had pushed away from the shore. Dead men tell no tales.

The survivor bias is the error of focusing on the information received from only one group, when it is impossible to obtain data from the other group. It is not necessarily about survival per se, but our example provides a good precedent. Indeed, collecting data from those who have not survived would require strong psychic skills! During the Second World War, mathematician Abraham Wald analysed war planes that managed to survive the battle and concluded that the spots most prone to damage were the middle, the tail, and the wings.

The military immediately started work on strengthening those parts of the plane - a clear case of the survivor bias. Wald did not notice that planes damaged in those spots were the ones that survived, while those planes that had been hit close to the engine or the cockpit simply did not return from the battlefield: those kinds of damage were truly fatal.

Just think about it: you may hear hundreds of stories of people who managed to walk a tightrope across a chasm and conclude that it is safe. But you will never hear from those who did not manage to cross over to tell their tale. At the bottom of the abyss, in the ocean depths, or at a cemetery of burnt war planes it is always quiet. That is why listening to and believing stories of those people who themselves do not understand how they managed to succeed is a classic example of the survivor bias. We listen to those who were lucky to find themselves in the right place at the right time and not commit any fatal errors. These are people whom dolphins only pushed towards the shore, so to speak. It would actually be more interesting to hear the stories of those who failed, in order to analyse their mistakes and find out which of those mistakes led to disaster. However, losers do not write books, do not give interviews and do not make public speeches with titles like "The story of my failure". My friends, try to only draw conclusions based on a full picture of events.