Causal Inference

09
Dec
3 min read

The Surrogate Trap: When the Mechanism Works But the Patient Dies

In the late 1980s, cardiologists thought they had cracked the code. They knew that patients who developed irregular heartbeats, premature ventricular contractions (PVCs), after a heart attack were more likely to die. They had drugs, encainide and flecainide, that reliably suppressed those irregular beats. The intuition was flawless: Suppress the

26
Nov
4 min read

When Every Company Becomes a Trialist

In 2014, during a major snowstorm, Uber ran a randomized test by turning off surge pricing for a subset of riders. Some waited longer. Others never got a ride at all. It wasn’t just a pricing tweak. It was a trial of behavior, supply, and equity. Trials, once reserved