An empirical socio-economic indicator of country-level food security

Economic access is a central dimension of food security, yet cross-country empirical work has limited measures that link the purchasing power of low-income populations to food expenditure across countries. We introduce the socio-economic index of food security (SEF), defined as the ratio between the per capita income of the bottom 20 percent of the income distribution and average per capita food expenditure. Using data from 110 countries, we examine the ability of SEF to explain cross-country differences in the prevalence of undernourishment (PoU), the Food and Agriculture Organization indicator of insufficient dietary energy intake. SEF explains a substantial share of cross-country variation in undernourishment. On average, a 1 percent increase in SEF is associated with a 0.25 percent lower PoU. The relationship is non-linear, with quantile regressions showing stronger effects at higher levels of food insecurity, where estimated elasticities range from −0.19 at the 25th percentile to −0.34 at the 95th percentile. Interestingly, an affordability measure based on the purchasing power of the poorest quintile captures cross-country differences in dietary-energy undernourishment more accurately than measures based on national-average income. SEF is therefore best understood as a globally comparable indicator of economic access to food, complementing household-level and multidimensional food security measures.