Standard assumptions

The title won’t make sense at first.

During lunch, I was mulling over the concept of calories. Calorie intake alone doesn’t provide you with an accurate picture of your health. It’s an objective measure, but it’s not very useful.

What is useful is knowing whether you’re eating more or less calories than usual. In this case it doesn’t even matter whether your measurements are objectively correct. It only matters that they’re consistent. (Fun fact: There’s some calculus behind the scenes!)

Say you eat a sandwich every day for lunch. Maybe you think it has 1000 calories. You’d be wrong, but it’s okay! If you add another sandwich to your diet and begin to put on an extra pound per week, it really doesn’t matter if it’s not objectively true that 7000 extra calories equals an extra pound. That’s because you’re probably only interested in whether your weight is going up or down.

If you’re trying to figure out the rate at which your weight will change, then the numbers start to matter. They still don’t have to be right, but the ratio has to be right. That is, it doesn’t matter so much whether a sandwich is 1000 calories or 20 calories, or whether an apple is 500 calories or 10 calories, so long as the ratio 2:1 is correct.

So objective data really isn’t important most of the time, depending on what you’re using it for.

As another example, let’s talk military metrics. Say the Army conducts “physical readiness tests” every year to determine whether the physical fitness of its soldiers for a battle situation. It’s impossible to determine this objectively without putting them in an actual battle and trying to kill them, because it’s difficult to artificially simulate the effects of adrenaline, stress, fear, and 3 days without sleep. The old colonel who runs ten miles per day might still be at risk for a heart attack, for all you know.

However, if the Army is only interested in continuous improvement (a useful peacetime goal), it only matters that the metric is consistent. Obviously the more closely it resembles “the real thing”, the better, but it’s also unnecessary to determine the direction of change.

So if you’re a general wondering whether the new fitness plan is working better than the old fitness plan, it doesn’t matter whether your metrics are objective. It only matters that they’re consistent. So if soldiers are gaming the test somehow (maybe by cutting corners to lower their 3-mile times), it only matters that they continue gaming it in exactly the same way.

About Aeoli Pera

Maybe do this later?
This entry was posted in blather, economics, math. Bookmark the permalink.

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