Notes on Thinking, Fast and Slow: The Slog of Statistics

When your kids first start learning to read, it takes a lot of effort. They have to remember the sounds that each letter makes, they have to combine those sounds together, and then try to figure out what word that combination of sounds actually is. Reading, at first, is slow and almost painful process.

Then one day, you’ll be driving along in your car, and you’ll hear from the car seat in the back, “SPEED LIMIT 55″. “EXIT 25B”. “CARPOOL LANE”. And then your kids have this sudden realization:

“Oh my goodness. I can’t stop reading! I can’t stop reading everything!

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Reading the first two parts of Daniel Kahneman’s Thinking, Fast and Slow flew by for me in a flash. Part III, however, was a bit of a slog. This section covers the various ways humans fail when it comes to statistical thinking. Kahneman notes that ideas like regression to the mean are among the most difficult for human beings to grasp. Kahneman does a pretty good job simplifying the issues, but it still takes some effort to understand.

To be honest, I took a couple of naps while working through that section. The best part, though, is that Kahneman explains why statistics are so tiring to work with.

We have two systems of thought, labeled System 1 and System 2. System 1 is fast, intuitive, effortless and automatic, while System 2 is slow, deliberate, and effortful. System 2 thinking uses up a lot of mental energy. Often, that effort seems not worth the trouble, so System 2 often just lazily accepts the intuitive suggestions from System 1, and moves on.

Unless you have a lot of practice in statistics, statistical thought is entirely a function of System 2. It’s slow. It takes effort and concentration. It requires a lot of mental energy to think in a statistically accurate way. It tires us out. We take naps afterwards.

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When your kids first start reading, it’s a System 2 process. It takes effort and concentration. But with practice, the System 1 gets trained to do it. System 1 is effortless and automatic. You can’t turn it off, ever. Once you learn to read, you can’t ever look at a sign again and NOT read it.

* * *

Most of us don’t encounter statistics enough in our daily lives for it to be transformed from a System 2 process to a System 1 process. For us, statistical thinking will always be a tough slog. But reading books like Kahneman’s can at least give us enough experience to recognize when proper statistical thinking is called for. When the stakes are high, we can understand just enough to say, “my gut feeling is X, but let’s run through the numbers to make sure”, instead of just accepting X.

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