br Sebastian Vollmer and colleagues April conclude that
Sebastian Vollmer and colleagues (April, 2014) conclude that “the contribution of economic growth to the s ibuprofen in early childhood undernutrition in developing countries is very small, if it exists at all”. Progress will therefore require a shift from “the so-called trickle-down approach of a growth-mediated strategy” to “direct investments in health and nutrition”. Using the same Demographic and Health Survey data as Vollmer and colleagues, we found that the association between economic growth and childhood undernutrition was strong and significant. We traced the findings of Vollmer and colleagues to specific shortcomings in their empirical approach—using a measure of real gross domestic product (GDP) that distorts country-level growth rates, overlooking the influence of a few highly unusual observations, and placing too much emphasis on short intra-survey intervals—and to limitations in their underlying thought experiment. Our interpretation of the evidence is that an effective attack on childhood malnutrition must be two-pronged, combining direct health interventions with vigorous efforts to advance economic growth.
Although we appreciate the interest of Stephen A O\'Connell and Caroline Smith in our work, we have to refute nearly all of their claims. Most importantly, their claim that they re-examine the same data and reproduce our results is incorrect. Their analysis is based on 121 aggregate-level data points without any covariates, whereas ours was based on the full microdata and a large set of covariates from 121 Demographic and Health Surveys, which included almost half a million observations. Their analysis re-examines very similar aggregate data as previous aggregate-level studies, and comes to more or less the same conclusions as these studies. It was the main innovation of our study to analyse the association between childhood undernutrition and economic growth at the micro level, accounting for individual-level characteristics, incorporating the repeated-within-country observations of gross domestic product (GDP) per capita in the statistical design by clustering standard errors and showing a large number of sensitivity analyses. None of the points made by O\'Connell and Smith question the robustness of our findings. Their claim that a few unusual observations push our results towards zero is incorrect and also related to their exclusive reliance on a bivariate aggregate analysis. If one just correlates 121 observations, some outliers can make a difference. This, however, bears no relation to our analysis, in which we also presented a large number of robustness checks and subsample analyses— including samples without the observations from the surveys in question—in all of which our results remain robust. For the outcome variable of stunting, O\'Connell and Smith exclude one observation from Armenia and one from Madagascar and claim that these two observations push our results towards zero. In table 3 of our study, we also reported population-weighted results, in which these two observations basically do not play any part (because of their small population compared with countries such as India), and still come to the same conclusions as everywhere else in the paper. The GDP per capita variable that we used was also chain-linked and therefore their claim that we used the inappropriate measure of real GDP is also without support.
In , Hannah Pieters and colleagues (September, 2016) analyse the effect of democratic reforms on child mortality across the world. We wish to highlight, however, that even with sophisticated causal inference techniques, such results cannot necessarily be interpreted as causal effects. First, the results are compatible with a number of different theories including that democratic reforms have no effect on health (ie, holding everything else fixed). Consider the cases of South Africa, Zambia, Mozambique, and Zimbabwe, all notably missing from the analyses but experiencing substantial democratic changes, analysed here using a similar synthetic control analysis (). No change is observed in South Africa after the end of apartheid in 1994. In Zambia, after reform in 1991, a reduction is observed but not until the price of copper tripled and GDP per capita doubled. In Mozambique, the large fall is likely attributable to the cessation of the civil war in 1993. And in Zimbabwe, democratic restrictions in 1987 did not precipitate an increase in child mortality.