Although people have been repeatedly found to underestimate frequencies of common
illnesses and overestimate those of rare illnesses, not much is known about this consistent
bias in risk perception, termed “primary bias” in the literature, as well as the origin of its
variations among different subpopulations. To fill this gap, we conducted a national survey
among a representative sample of the French population (n= 3,245) to compare the
perceived and actual prevalence of chronic illnesses, and to test the hypothesis that …

Although people have been repeatedly found to underestimate frequencies of common
illnesses and overestimate those of rare illnesses, not much is known about this consistent
bias in risk perception, termed “primary bias” in the literature, as well as the origin of its
variations among different subpopulations. To fill this gap, we designed and implemented a
national survey to compare the perceived and actual prevalence of common illnesses, and
to test the hypothesis that numeracy may play an important role in the accuracy of judgments …