Survivorship Bias: How to Avoid Bad Advice

During World War II, the British military was losing their bomber aircrafts at an alarming rate.

As they were flying over enemy territory, they were being shot down so often that they decided to add armor to their planes.

But they couldn’t shield the entire surface of their aircrafts.

That would make them too heavy to take off.

So, they put the armor only in the most critical places.

Where Are the Bullet Holes?

To find out what those areas were, they carefully investigated the aircrafts that came back from battle and noted where they had been damaged the most.

The investigators found that the majority of the bullet holes tended to be on the wings, around the tail gunner, and down the center of the body.

Now, let’s imagine that you were in charge of the investigation.

With that information at your disposal….

Where Would You Put the Armor?

Most likely, you would want to do what the real commanders planned on doing.

They wanted to shield the parts that had the most bullet holes; the wings, the tail gunner, and the center of the body.

It seems like the obvious choice, but it would have been a terrible idea.

Why? Because remember; the investigators had only considered the aircrafts that survived their missions.

All the planes that had been shot down had not been taken into account.

So, what the holes in the examined aircrafts represented were the areas where the bombers could take damage and still make it home.

No Damage? Shield It!

Counterintuitively, it was the unharmed parts of the examined planes that needed the armor.

Because if those were hit, the aircraft would be lost, and it wouldn’t have shown up in the investigation.

Luckily for the British military, statistician Abraham Wald pointed all that out and helped them avoid a crucial mistake.

But in everyday life, we fall for the survivorship bias all the time, and it has significant implications on our judgment and decisions.

The Successful Dropout Myth

Consider, for example, the famous stories of how successful people like Richard Branson, Bill Gates, and Mark Zuckerberg all dropped out of school.

Learning about them, many people conclude that you don’t need a college education to succeed.

But for every Branson, Gates, and Zuckerberg, there are thousands, if not millions, of other entrepreneurs who dropped out of school and failed in business.

We just don’t hear about them, and so we don’t take them into account.

How to Counteract the Survivorship Bias

When you pay attention to the winners and ignore the losers, it’s difficult to say if a particular strategy will be successful.

So, whenever you’re presented with a success story, ask yourself if it provides a complete picture, or if it’s only taking survivors into account.

That way, you’ll make more accurate judgments and avoid bad advice.

This article is an excerpt from my book The Decision-Making Blueprint.