Fig. 4: Magnitude and components of transboundary SDG interactions by income group.

a Spatial interaction index by income groups. b Share of the components of spatial interaction index by income groups. The sum of synergistic effects and trade-off effects equals the spatial interaction index. There are four income groups: high, upper-middle, lower-middle, and low income groups (Supplementary information Table S4). The blue in the pie charts represents the proportion of transboundary synergistic effects.