Part 3/11:

This discrepancy is known in epidemiology as the Will Rogers phenomenon, named after the famous American humorist who joked about how moving a population from one state to another could artificially raise the average IQ in both. The mathematical principle is simple yet profoundly impactful: by reclassifying individuals into different groups with advancements in detection, the average survival within those groups appears to improve, even if nobody is living longer overall.

How It Works: An Example in Cancer Detection

Consider two populations in 1970:

• Healthy people with an average remaining lifespan of 30 years.

• Cancer patients who survive about 5 years post-diagnosis.

Fast forward to 1990, with advanced imaging technology: