Fig. 1From: Using cluster analysis to reconstruct dengue exposure patterns from cross-sectional serological studies in Singaporea The six clusters of 509 seropositive individuals obtained with the K-means algorithm. The x- and y-axes represent the two principle components from principle components analysis and account for 48% and 30% of the variance in the data, respectively. Colour shading represents the density of the data. b The four PRNT50 vectors used in the main analysis plotted in the two-dimensional principle component planeBack to article page