So the story goes, as told by Stephen Sigler, Nature May 1989:

"The US military studied fighter planes returning from missions to try to improve their survival rate and were considering adding heavy armour to those parts of the plane that tended to show the greatest concentration of hits from enemy fire, until statisticians pointed out the fallacy of that argument. The more vulnerable parts of the plane were those with the fewest hits; planes hit there tended not to return at all. The single most vulnerable part, the pilot’s head, was without serious scar in the sample of planes that returned."

It’s easy to draw correlations from what we see in front of us. But what we see usually represents just a small part of what has happened. Focusing on the evidence we can easily see at the expense of that we can’t leads to survivorship bias. To say it another way, when Bill Gates drops out of college and starts Microsoft it might seem like dropping out is a path to success for others too, but that ignores all the dropouts who didn’t create Microsofts and consequently you didn’t hear about.

Silent evidence — the evidence that we don’t or can’t easily choose to consider — is a term from Nicholas Nassim Talleb.

When trying to discover the veracity of the planes story I enjoyed Bill Casselman’s American Mathematical Society article on The Legend of Abraham Wald. The postscript points to some of the source behind the story including a mention of Stephen Sigler’s letter in Nature quoted above.

I covered survivorship bias before but like this story so much I thought it was worth doing again.

Survivorship bias

I hadn’t given much thought to hope, beyond it being a nice feeling to have, until I heard of CR Snyder’s cognitive model for hope which shed a new light on it for me. He proposed a model of hope where (paraphrasing) an individual may be hopeful if they have:

Goals they desire. If you don’t or can’t picture any future state you’d like then you won’t have a lot of hope.

Pathways. You need to see some ways that you may make step-by-step progress towards a goal.

Willpower or agency. You need to be motivated and believe that you have the ability to succeed at your goal.

With all of these you can imagine feeling hopeful. Without any one of them and you probably won’t so much.

The mountain is the Ogre, a wholly impossible looking peak scaled by Doug Scott and others for which I would have had zero hope to climb (no pathways, no willpower) and yet they remarkably did.

HT once again to Brené Brown in Dare to Lead.

Hope

“Just remember that finishing lines are good, but their most important role is to get you over the start line in the first place.”

This little piece of wisdom is from Stevie Smith (not the poet). Stevie embarked on a human-powered journey around the world — Expedition 360 — and reached Hawaii under pedal power*. I learned about him from a little chapter in One Man and His Bike by Mike Carter. The chapter where he speaks with Stevie I immediately reread as soon as I finished it.

Mike also shared this deeper and more poetic version of the same insight:

“Happiness is the acceptance of the journey as it is now, not the promise of the other shore”

*Stevie’s companion Jason Lewis completed the circumnavigation of the world 13 years after they began.

Finishing lines