The health bias is... An unseen trait among a collection of individuals, who do not know what they have. In fact, they don't know how good they've got it, because that is part of the definition.
So far in their lives, they have not directly experienced a condition that was neither deadly nor fixable. They have had cold and flu, some of them may even have had a headache. I'll take a non-statistically relevant example: I knew a guy once who reported to have never felt ill in his life, apart from the occasional sniffle and a particularly bad case of flu which set him back 1 whole day in bed. He genuinely had no idea why people got ill, and why they needed time off work.
More than that, you can find these odd people to collect together. Why? Because it is a sort of data bias; a filter which selects those who, through no particular doing of their own, can do a lot more than the rest of us genetically inferior beings can accomplish.
If you were to somehow find these healthy people, they'd be mostly together in daylight hours, Monday through Friday. I'm willing to bet they have a high chance of working in the same buildings, together, and in teams.
I want to talk about this in more depth, but first an optional aside:
Aside
My posts generally try not to beat about the proverbial bush because adding in so many exceptions like "for the most part" and "within certain parameters" and "for the parts of the world I can only consider because I'm not omnipotent" start to dilute the overall quality of the message attempting to be delivered. Reader, you will have to assume I am only human. So henceforth, I aim to be as direct as possible, and you will have to give me the benefit of the doubt on the exceptions I didn't add in. (Aside 2: I'm reminded of the learning philosophy of Richard Feynman, go look that up again, you should too)
What do you think of when you think of the word "health"?
Images suddenly conjure up in your mind... probably similar to these standard stock photos of "health"... in all probability they will seem normal to you, even down right expected...
... because those are the connotations of health which are handed to us in the media and from common society. In that way, we all think somewhat alike. (If you disagree, I think watching a Derren Brown show should at least put doubt in your mind)
That isn't what health is
Health is the thing that you never have to think about, because everything works perfectly, and you don't have to spend conscious effort managing it. You may well go running every day, eat well, socialize well, and exude the work hard/play hard model. But I see that as sort of a mini side-effect of health, rather than some consequence of the activities. Don't mistake that for saying fat people can't minimize their chance of cancer by slimming down; they can. But the person with a chronic condition (one which will never go away) can be physically and mentally stifled by it, in ways which cannot be fully comprehended unless you have that chronic condition itself. Equal opportunities do not exist because of this inability to experience the other side.
Health problems have a nasty habit of interacting in strange and bizarre ways, which means the 'running' that can make you better will make you feel worse, the 'eat well' should work but causes more problems, the 'socialize well' doesn't happen from a lack of energy, and 'work hard/play hard' is just a motto from those who are healthy (and they don't know it).
So what is the health bias?
You perform at your best, always, and due to no fault of your own, you have a better life. Over time, this could result in better opportunities, schooling, jobs, money, sex, family holidays in Switzerland, and iconic furniture from an upmarket IKEA brand nobody else has heard of. That's partly a misconception; maybe they'd also be great black market traders, expert-level drug smugglers, and of course a few crafty politicians (and their speech writers).
I suppose in past times the "health bias" was far more simple. If you were alive by the age of 20 then you were definitely in the health territory, otherwise you were dead. It wasn't so much a bias as just basic Darwinism. But we don't have that any more, as people don't always die from their chronic conditions, just lead difficult lives. I suppose you could sort of restore it in a futuristic dystopia, where couples select their favorite sperm from a catalog of profitable and high-flying accountants, for a certain price. But that would never happen...