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Figure 2 | EPJ Data Science

Figure 2

From: Socioeconomic biases in urban mixing patterns of US metropolitan areas

Figure 2

Socioeconomic stratification matrices. (top) Empirical stratification matrices \(M_{i,j}\), showing the probabilities that individuals from a given class visit to places of different classes. The darker colour shades of bins represent larger visiting probability. Matrices of Houston (Fig. 2(a)), New York (Fig. 2(b)) and San Diego (Fig. 2(c)) all show strong stratification patterns, indicating that people tend to visit most likely places with similar status. The normalised stratification matrices \(N_{i,j}\), defined as the fraction of the empirical and randomised stratification matrices. After normalisation, such stratification pattern becomes less evident for New York (Fig. 2(e)) and San Diego (Fig. 2(f)) but quite persistent in Houston (Fig. 2(d)). Similar matrices computed for other urban areas are available in Additional file 1, Section B. (bottom) Mean of matrix element \(N_{i,j}\), computed separately for the upper, lower, and main diagonals. Among 20 urban areas, 12 of them (including Houston) have higher mean values for upper diagonal elements, indicating dominant upward visiting biases. In contrast, we see dominant downward visiting biases in San Diego, while mean values of upper and lower diagonal elements are almost indistinguishable in New York (respectively 0.932 and 0.945)

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