instrumental variables

Senior DS loops test causal reasoning past the randomized A/B test. The signal is naming the quasi-experimental method that fits and stating the single assumption it lives or dies on. Here is the answer for when randomization is off the table.

IV is the causal tool people name but can't defend. The signal is articulating the two conditions an instrument must satisfy, why one is testable and one is not, and what 2SLS actually estimates. Here is the answer.