Carl T. Bergstrom sur Twitter :
▻https://twitter.com/CT_Bergstrom/status/1427767364712419330
Un #paradoxe_de_Simpson, pour expliquer l’apparente diminution de l’efficacité du #vaccin contre les cas sévères de #covid-19 ?
4. This results are confounded by age. Irrespective of disease status most unvaxxed are young; irrespective of vaccine status most severe disease cases are old.
This creates counterintuitive statistical result. VE overall is far lower than VE in under 50 or in people over 50.
5. You may recognize this as an instance of Simpson’s paradox. In this case, both cohorts have a much higher VE than the VE of the two cohorts aggregated together. This seems paradoxical, but results from the confounding described above.
