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Comment by antidesitter | Hacker News Reader

What is “luck” supposed to mean in your diagram?

Consider children of immigrants. Look at the ones who are tall, taller than their parents. Are they tall because they got good nutrition, etc.? Many people supposed that they have natural tallness genes and their parents were only shorter because of tough times in the old country.

Now look at their children, the grandchildren of the immigrants. They tend back toward average.

The tall kids were tall because, in part, there is a natural variation and they happened to get on one side of the bell curve. Luck, if you will.

Any contributing factor outside your base ability. Weather (too hot, too cold, just right), mental state (did someone put you on edge, sleep poorly), etc.

So some of those are more or less under your control. Maybe you can control your mental state better than me. Me, a particularly stressful day at work doesn't lend to the quiet mind I need for a run. Those are my 36 minute 5km days. But nicer weather, seeing the geese on the pond as they migrate, can put my mind at ease even on those stressful days and I might pull off one of my faster runs. I can't control that.

so performance is ability plus the contribution of all other factors that are not ability.

tough to argue with that one.

I mean, we can break out luck to be all the various factors. But it can be summed up into one (for the purposes of this discussion). And each of those will still have some mean that they tend toward. The weather, outside San Diego, isn't going to be perfect year round. Your relationships (impacting mental state) won't all be rosy. Your sleep can be interrupted by a neighbor moving in at 3am. Though that last one is atypical. And if it happens, and your race time is 8 minutes instead of the average of 7, you should still expect to be closer to 7 the next race barring similar misfortune.

I think the main point is that performance depends on some factors that we can reasonably expect to remain constant between races ('ability'), and others that are likely to vary quasi-randomly between races ('luck').

Those names are imperfect but the underlying logic is sound: the winner of a race is relatively likely to have both high 'ability' in himself, and higher 'luck' than usual for that particular race. In the next race, his 'ability' will remain high, but he will probably have roughly average luck.

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