Evidence-appraisal glossary
Will Rogers Phenomenon
The Will Rogers phenomenon is an illusion in which survival appears to improve in every disease stage without anyone actually living longer, simply because better tests reshuffle patients between stages. It is also called stage migration.
Also called: stage migration, stage-migration bias.
When more sensitive imaging finds small spread that was previously missed, patients once labeled early stage move to a later stage. Those reclassified patients tend to fare worse than others in the early group but better than others in the late group, so the average outcome rises in both. Comparing outcomes across eras with different diagnostic technology can therefore mislead, mimicking progress that is not real.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.