President Trump said each of the missile defense interceptors at the
Ground-based Midcourse Defense site in Alaska has a 97% chance of shooting down a North Korean missile and that two would have a 100% chance.

Statistics don't work like that, at least that's not
how it was taught where Jeffrey and Aaron went to school. We discuss
how to think about missile defenses and statistical risk, while Scott
joins us to explain the online calculator he built for just such a
problem.

 

Links of Note:

Mostly Missile Defense's List of Claims about GMD Effectiveness.

The Washington Post's Fact Check on President Trump's 97% claim.

Joshua Pollack's article on the 97% claim on Defense One.

Scott's been fiddling with missile defense calculators and put together a few helpful tools:

The Simple Model (pulled from Wilkening's work), but without radar/sensor probabilities. This calculator is used to estimate the probability of a multilayer missile defense architecture intercepting X number of incoming warheads.

Another Simple Model based calculator, but with a very basic estimation for sensors and tracking probabilities, also based on Wilkening's writings.

Scott's under-construction experimental tool for sticking these probabilities on a map (with examples!).