[Question] Where to find Base Rates?

As we are all aware from Think­ing, Fast and Slow, one of the largest de­ci­sion-mak­ing er­rors we make is the Base Rate Fal­lacy. Just to re­mind you—the er­ror is that we don’t cor­rectly ap­ply prob­a­bil­ity refer­ence classes to our­selves.

Two ex­am­ples:

  • The like­li­hood of win­ning the lot­tery is x, but I am more likely to win than x.

  • 1 in x peo­ple will get lung can­cer from smok­ing, but I won’t.

This is all well and good, but my ques­tion is where you go about ac­tu­ally find­ing x. In other words—where do you find your base rates? Any par­tic­u­lar repos­i­to­ries of knowl­edge that we should know about? Any pro­cesses that we should fol­low?

Let’s say you’ve de­cided you want to re­duce your risk of get­ting Coronary Heart Disease. Is your first stop to go to WHO and gather their list of recom­men­da­tions, or some­thing else?