Encara no tenim significats per a "ecologic studies".
1In ecologic studies, the exposure status of groups is often defined by the proportion of individuals exposed.
2In ecologic studies, covariate levels of groups are often quantified as the prevalence of a dichotomous covariate.
3In contrast to other ecologic studies, we found no consistent association between radon level and cancer mortality.
4Ecologic studies showed very high densities of several species of sigmodontine rodents in the area.
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