Predictive Models

Fishnu by our miner's lettuce
Fishnu by our miner’s lettuce

The Miner’s Lettuce is going to seed and will soon be gone. I told Fishnu about how the miner’s of the California Gold Rush would suffer from Vitamin C deficiency over the Sierra winters, until this very edible plant, high in Vitamin C, sprouts up in the very early Spring, curing their scurvy. The funny thing is they didn’t know pine needles, edible, but yucky, and more than readily available during the winter, are rich in Vitamin C.

Fishnu clapped his fins slowly in mocked amazement at my great wisdom.

He then asked, “If you build a predictive model that is correct 99% of the time, is that a good model?”

Me: Yes, but I think any model as good as that is pretty obvious to people already.

Fishnu: That’s true, obvious to people, but not to a computer. So how many models are out there in the world making guesses about you? Your Airbnb ratings, your Uber ratings, LinkedIn, Facebook, credit scores, health risks, security threat …

Me: Oh … thousands … millions …

Fishnu: Are they mostly 99% correct?

Me: No! Some customers have said to me that all they want is for it to be better than a coin toss. In fact, if it’s too good, they say it’s “overfit”, it doesn’t “generalize”.

Fishnu: What does this “generalize” means?

Me: It means because we don’t know everything about everything, we need to make some assumptions about people or things to make decisions about a lot of people or things. So if you’re a rectangle and there isn’t a hole for rectangles, you’re shoved through the square hole.

Fishnu: How many predictions would it take before they are wrong? Once in a billion years?

Me: Hahaha! Billion years!? Probably every other minute some model somewhere is making a wrong prediction about you, even if all were correct 99% of the time!

Fishnu: What happens when they are wrong, when you don’t fit the model?

Me: Nothing really. Most of the time, the worst is that you’re targeted for a sale, they call you during dinner, you tell them not to call anymore, and you’re the asshole. Sometimes it is worse than that – they tell you you’re morbidly obese at 220 pounds, you diet to 180 and feel weak.

Fishnu: Can people ever make these predictive models perfect?

Me: No because we’ll never know everything about everything. So … what do we do?

Fishnu: Erase the illusions of the boxes you’ve been taught to draw around things. You will see the process and not those things. Your brain will resist because those beliefs are wired there. It takes years of training to rewire them, so just ignore them now and feel what is right here right now.

Me: That’s it!? The “Now” thing? Is that all there is?

Fishnu: Geez! What do you think I’ve been saying?

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