The PR BlogMedia & PsychologyBehavioural PsychologySurvivorship Bias—Abraham Wald and the WWII Airplanes

Survivorship Bias — Abraham Wald and the WWII Airplanes

Don't let the success of others dictate your strategy.

Cover photo: @jerrysilfwer

Survivorship bias is a tricky fal­lacy to deal with.

We’re all mes­mer­ised by suc­cess stor­ies. But study­ing those who are suc­cess­ful isn’t always the best idea.

You might suc­cumb to sur­viv­or­ship bias.
You might bet on flawed strategies.

Here goes:

Abraham Wald and the Allied Aircrafts

During World War II, the Allies stud­ied Nazi dam­age to their fight­er planes. Their study res­ul­ted in this dot­ted illustration:

Survivorship-Bias - Missing Bullet Holes - Abraham Wald
This air­craft seems to suf­fer from some mys­ter­i­ous condition.

The ana­lys­is of these dam­ages res­ul­ted in the idea that the Allied Forces should rein­force their fight­er planes in the areas show­ing the densest clusters of red dots. 

A stat­ist­i­cian by the name of Abraham Wald dis­agreed. Instead, he sug­ges­ted that they rein­force sur­faces with no red dots.

Wald was right, of course. By study­ing planes that some­how returned home, the red-dot­ted areas indic­ated non-fatal dam­aged regions. 

If it had been pos­sible to study all the planes shot down and des­troyed by the Nazis, the research team would likely have found an inverse pattern.

World War I and the Soldiers’ Helmets

In anoth­er example, we focus on a seem­ingly coun­ter­in­tu­it­ive phe­nomen­on that emerged dur­ing World War I. 

As mil­it­ary forces began to increase the issu­ing of hel­mets to sol­diers to pro­tect them from the per­ils of the bat­tle­field, an unex­pec­ted trend was observed: the num­ber of wounded sol­diers surged dramatically. 

At first glance, it may seem that the hel­mets were para­dox­ic­ally mak­ing it easi­er for more people to get hurt. The crux of this para­dox lies in the shift­ing dynam­ics of the cas­u­alty statistics: 

As hel­mets were intro­duced and dis­trib­uted more widely, they sig­ni­fic­antly reduced the num­ber of fatal­it­ies on the bat­tle­field. Soldiers who would have pre­vi­ously suc­cumbed to their injur­ies were now sur­viv­ing. Consequently, these sol­diers were clas­si­fied as “wounded” rather than “dead.”

This shift in cat­egor­isa­tion cre­ated the illu­sion of increased injur­ies when, in real­ity, the num­ber of fatal­it­ies had decreased. 

The Fallacy of Survivorship Bias

These examples under­score the import­ance of con­sid­er­ing the lar­ger con­text and being cau­tious about con­clu­sions based solely on super­fi­cial data.

Both stor­ies are excel­lent examples of a par­tic­u­lar fal­lacy — sur­viv­or­ship bias.

Survivorship bias, sur­viv­al bias is the logic­al error of con­cen­trat­ing on entit­ies that passed a selec­tion pro­cess while over­look­ing those that did not. This can lead to incor­rect con­clu­sions because of incom­plete data.”
Source: Wikipedia

We often can’t help being enticed by suc­cess stor­ies in pop­u­lar cul­ture and busi­ness. But their stor­ies can lead us to fal­la­cious conclusions. 

  • Remember: cor­rel­a­tion does not equal causation.

Few think to study those who turned out to be unsuc­cess­ful. In terms of data sets, this is too bad since the unsuc­cess­ful typ­ic­ally out­num­ber the suc­cess­ful by a vast margin.

Read also: 58 Logical Fallacies and Cognitive Biases

Please sup­port my blog by shar­ing it with oth­er PR- and com­mu­nic­a­tion pro­fes­sion­als. For ques­tions or PR sup­port, con­tact me via jerry@​spinfactory.​com.

Jerry Silfwer
Jerry Silfwer
Jerry Silfwer, alias Doctor Spin, is an awarded senior adviser specialising in public relations and digital strategy. Currently CEO at KIX Index and Spin Factory. Before that, he worked at Kaufmann, Whispr Group, Springtime PR, and Spotlight PR. Based in Stockholm, Sweden.

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