# **Data Appendix**

The data used for this paper are derived from all of the Demographic and Health Surveys publically available by end-2005. Table A1 provides details on the countries, years, and sample sizes of these surveys. (More information on individual surveys can be found at www.measuredhs.com.) To give a broad overview of the data we first calculate infant mortality for individual country-year cells, and present a scatter plot of infant mortality and log per capita GDP in Figure A1. Infant mortality varies considerably in our sample, and there is a clear negative association between infant mortality and GDP. On average, (with these “averages” imputed from a nonparametric regression) countries at the 10<sup>th</sup> percentile of log GDP have an infant mortality rate that is more than twice as high as those at the 90<sup>th</sup> percentile of log GDP (130 deaths per thousand, compared to 56 deaths per thousand).

We next compare the estimates of infant mortality we construct with estimates of infant mortality in the World Development Indicators (WDI) data base (World Bank 2007). Aggregate data like the WDI have been used frequently for research on the relationship between income and infant mortality in the developing world (for example, Pritchett and Summers 1996; Jamison et al. 2004; Deaton 2006). The WDI data are based on data from both the United Nations Statistical Division and UNICEF. These two bodies collate data from administrative records (civil registration, population registration), population and housing censuses, and social and demographic surveys. Demographic smoothing processes are then used to generate bi-decennial estimates of infant mortality (World Bank 2007b). Given the difference in methodologies and data sources used to construct the infant mortality series in the WDI series and in our own, we would not expect the estimates for any given country-year to be identical across both data sets but we would hope there to be sufficient overlap and similarity. Figure A2 plots the estimates of infant mortality we construct from the DHS against the WDI estimates, for all years of overlap. Estimates of infant mortality from the DHS and WDI tend to be very highly correlated with each other. The average infant mortality rate in the WDI series for countries and periods that also have DHS is 82.8, that estimated exclusively from the DHS is 85.3. The R-squared in a regression of the WDI infant mortality on the DHS infant mortality is 0.81.

As a final check on our measures of infant mortality we exploit the fact that, for countries with more than one survey, we can construct more than one estimate of infant mortality for a given year. There are 346 country-year observations with more than one estimate of infant mortality in our data. (In our main results, including in Figures A1 and A2 above, we take the average of these estimates.) When we regress the infant mortality rate for a given country-year calculated from the later survey on that calculated from the earlier survey, the coefficient is 0.90 (with a standard error of 0.03). This result is consistent with a close relationship between the two measures of infant mortality in the presence of some attenuation bias from measurement error.

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