Biases and effectsAbraham Wald, 1943
Looking at the bullet holes on planes that came back and armouring those spots is wrong. Nobody gets to interview the planes that did not.
In the Second World War the military mapped bullet holes on returning bombers. Many on the wings and fuselage, few around the engines and cockpit. The plan: reinforce where the holes are.
The statistician Abraham Wald said the opposite. Armour the engines.
You are only seeing planes that made it home. Holes in the wing mean a wing can take a hit. No holes on the engine because planes hit there never came back. The blank spots in the data were the fatal ones.
What vanished takes the fact of its vanishing with it. Successful companies get books; companies that did the same things and died do not. So "what winners have in common" quietly includes things the losers had too.
Everyone knows the billionaire who dropped out of college. The dropouts who founded companies and disappeared outnumber them hundreds to one, and you cannot name a single one.
When your sample is only the survivors, the lessons you draw are not how to survive, but what survivors happened to look like.
Ask: "where are the people who did this and it did not work?" If you cannot find them, they are not absent — they are invisible.
Find the denominator. Ten success stories tell you nothing until you know how many tried.
It applies to your own story too. "This always got me through before" often means the times it did not have been forgotten.
"They built things to last back then"
Said while looking at a forty-year-old fridge that still runs. The forty-year-old fridges that broke were thrown out decades ago and are invisible. What remains is the sturdy ones by definition.
The founder interview
"I got up at four every morning." "I trusted my gut." The people who did the same and failed do not get profiled. Before collecting the habits, ask how many people with those habits are gone.
The advertising page on this site
This is why the `/ads` page will show every month's numbers, not just good ones. Showing only the good months is this bias in action — readers would assume it is always like that.
If you take one thing
Every success story in front of you is a plane that came back. Spend a moment on where the holes are not.
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