SURVIVAL BIAS: what it is, causes and examples

It is easy to see and pay attention only to the successes and not to the failures, which are forgotten. This phenomenon, which derives from selection bias, is called survival bias: a selection error (of objects, of people, of data), precisely based on the fact of trusting and taking into account exclusively the success stories, instead, the cases are omitted negatives.

Survival bias is among the well-studied cognitive distortions in psychology, and examples of this can be found in across the board, as success is highly visible in everyday life and people systematically underestimate its chances of achieve it. With this Psychology-Online article we will discover what is survival bias, what are its causes and some examples.

Index

1. What is the survival bias or Neyman fallacy
2. Causes of survival bias
3. Examples of survival bias

Survival bias or survival bias is the logical error made when

The term "survivorship bias" was first used by Allied engineers in World War II. During the conflict, the statistician Abraham Wald took notoriously the survival bias in his calculations when considering how to minimize bomber losses to enemy fire, believing that planes that did not return from battle had to be examined, without observing the bullet holes in which they did.

In the medicine, survival bias is also known as Neyman's fallacy, which consists of using prevailing cases for case-control studies: prevailing cases are also surviving cases and these may not be representative of all cases. One of the situations that originate this bias is the use of cases detected in screening campaigns, since these cases may have a different evolution than the whole.

Survival bias also describes one of the most common - and important - flaws in data analysis. In fact, survival bias tends to skew the data in only one direction, making the results look better than they are. A phenomenon ignored in the past by the industry, which can lead to significant distortions in the presentation of performance data, which in turn can lead to investment decisions wrong. In particular, he is accused of overestimating return on assets.

The human brain is programmed through evolution to discover deviations, and that is why we are fascinated by success stories of those who stand out, remembering much more information about success than other news.

Survival bias is a predominant cognitive bias, which can be attributed to misunderstanding fundamental cause and effect, in particular as regards the concept of correlation with the causality. Although correlation and causation may exist, correlation does not imply causation. Causality refers to cases where action A causes the result of B, while correlation is simply a relationship, and survival bias causes individuals to believe that the correlation is causal, leading to a misunderstanding of cause and effect.

Survival bias can lead to overly optimistic beliefs because failures are ignored, but it can also lead to the false belief that successes in a group have some special property, rather than being a mere coincidence.

In this article you will find all the types of cognitive biases.

Once we are familiar with the idea of ​​survival bias, we can begin to detect it everywhere: for example, a gym could introduce those who have quickly toned up after having been to their facility but of course what they never show are those who have signed up but got nothing but a bank account exhausted.

The most famous example of survival prejudice dates back to World War II. At that time, the American military asked mathematician Abraham Wald to study the best way to protect planes from shooting down. The military knew the armor would help, but they couldn't protect the entire plane or they would be too heavy to fly well. Initially, his plan was to examine the aircraft returning from the fight, see where they had been hit the most (the wings, around the tail gun, and the center of the body), and then reinforce those areas. But Wald realized that they had fallen prey to the survival bias, because his analysis was missing a valuable part of the painting: the planes that had been hit but had not returned. Consequently, the military planned to assemble precisely the wrong parts of the planes: the bullet holes that were seeing indicated the areas in which a plane could be hit and continue flying, exactly the areas that did not need reinforcement.

This article is merely informative, in Psychology-Online we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.

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