Statistics

One train/test split can make one model look better than it is and another look worse, in the same experiment. Here's what that looks like with real numbers.

Fast-time simulation models hours of operation in seconds, so you can test decisions too risky or costly to try for real. What it is, how a study works, and when a digital twin is worth building.

Fifteen ways regression output gets misread, with the symptom, what it actually means, and how to check. Every one came from a real model.

Alone it reads -0.0054. With seven other predictors, +0.0154. Both significant. Why hunting for the guilty variable is the wrong instinct.

The smoker coefficient is $24,330. That does not mean quitting saves anyone $24,330, and no amount of significance will make it mean that.