We additionally explored the robustness of the results to alternative
approaches to implementing the RD design. SI Appendix,
Table S9 reports a set of goodness-of-fit tests that lead us
to emphasize modeling distance from the Huai River with a cubic
polynomial in latitude. SI Appendix, Table S10 documents that
a first- or second-order polynomial in latitude best fits the data in
the sample that is restricted to locations within 5° latitude of the
river, and that the results are qualitatively similar using either
approach. SI Appendix, Table S11 reports on specifications that
allow the polynomial to differ to the north and south of the river.
The goodness-of-fit statistics support separate quadratics north
and south of the Huai River, and this specification suggests
a somewhat smaller increase in TSPs at the border but a larger
decline in life expectancy.