CORRELATION has published a new brief report entitled “Fisman et al.’s Psi (Ψ) index is ill-defined and leads to absurd interpretations” authored by Joseph Hickey and Denis G. Rancourt. The report shows that modeling claims, based on a novel mathematical construction (Ψ), that unvaccinated people disproportionately contribute to the infection risk of vaccinated people are… Continue reading Fisman et al.’s Psi (Ψ) index is ill-defined and leads to absurd interpretations