Figure 4

Principal component analysis (correlation circle) of veterinary article output and demographic and economic variables. The first principal component (horizontal axis) accounts for 39.8% of variation and comprises the highly correlated cluster of gross domestic product (GDP) and the number of articles (total, small animal [SA], equine [EQ], food animal [FA], miscellaneous [Misc]). The second principal component (vertical axis) accounts for 19% of variation and comprises the opposing clusters of agriculture value-added and % rural population (Pop.) versus gross national income (GNI) per capita, research and development (Res & Dev), and % urban Pop. Variables close to the center are less strongly correlated with variables far from the center in the same cluster because some information is carried on other axes. %SA, %EQ, %FA, and %Misc refer to the proportions of articles in species-specific journals. Bibliographic data [18] from 1996–2010 were used in the analysis; demographic and economic data were primarily from 2010 [24].