The logic in ecological: I. The logic of analysis.

Abstract

This paper addresses ecological studies in public health research in terms of the logic of their analysis. It makes several distinctions between studies based on ecological and individual units. First, it identifies the variables common to both types of study and those particular to ecological studies. Second, it shows how ecological and individual units combine in two classes: unmixed (purely ecological, purely individual) and mixed. Third, it details how the relationships among and between individual and grouped units (expressed in terms of regression coefficients between independent and dependent variables) yield four coefficients: for all individual members; for all groups; for all individuals within each group; and for all individuals within groups (a weighted average). Equipped with an understanding of the dimensions involved at ecological and individual levels and of the relationships between them, researchers are in a position to exploit the public health potential of the ecological approach.

Relationship between premature mortality and socioeconomic factors in black and white populations of US metropolitan areas

“…24 Given that the individual and ecological context levels are distinct, their properties and characteristics cannot be entirely predicted by each other. [25][26][27] In studying social, economic, and cultural features of Glasgow neighborhoods, MacIntyre and her colleagues demonstrated that although individual social class may be correlated with where one lives, the specific features of the areas themselves are independently related to population morbidity and mortality. Among others, these features included: networks of social support, crime rates, quality and tenure of housing stock, and neighborhood reputation.…”

The association between individual and contextual factors and functional dentition status among adults in Rio Grande do Sul State, Brazil: a multilevel study

“…Edentulous persons usually have lower incomes and less schooling, less access to services, and poor self-rated oral health 15 . However, it has been argued that explanations based purely on individual data are insufficient and fail to capture important determinant of health and disease, the characteristics of groups and contexts to which the individuals belong 16,17 . The literature is thus limited on the influence of contextual aspects on oral health in individuals and groups 18 .…”

Risk factors for bovine herpesvirus-1 seropositivity

“…As those authors reported, clustering is a key feature of the BHV-1 1998-serosurvey data, with an intra-cluster (intra-herd) correlation coefficient of 0.64. Exposure to infectious agents probably results in a more-homogeneous serological status of animals within clusters as measured by the intra-cluster correlation coefficient (Donald and Donner, 1987;Rothman, 1990), because the interrelatedness of incidence and prevalence is the very characteristic that defines infectious diseases (Koopman et al, 1991;Susser, 1994a;De Jong, 1995). Consequently, it cannot be assumed that the animals are independent units (Schukken et al, 1991;Elbers and Schukken, 1995;Cameron and Baldock, 1998), because compared to other population members, animals within clusters have a higher chance of becoming infected once the infection is introduced into the herd.…”