Abstract
A recent systematic review by Zurcher (World Develop 98: 506–522, 2017) finds that humanitarian aid unequivocally increases violence. This note demonstrates that this conclusion is not warranted by a careful examination of the studies included in the abovementioned systematic review. We highlight the incorrect interpretation of econometric results and the lack of robustness in the sampled studies. We also replicate three studies, and report mixed evidence on the effect of humanitarian aid on violence.
Notes
The review also provides a detailed description of the potential causal mechanisms between development aid and violence.
We have reached out to the author to get access to the dataset, but have not received a response.
Note that these papers have been cited, respectively, 56, 46, and 6 times according to Google Scholar (as of 5/14/2019). Zurcher (2017) has been cited 16 times. The moderate amount of citations should not understate the influence of these papers. Their findings are implicitly translated into critical policy guidance (e.g., Central Intelligence Agency’s World Threat Assessment 2014; Global Food Security Act 2016).
The reader is referred to Zurcher (2017) for an in-depth discussion of the links between humanitarian aid and violence. We briefly summarize the key mechanisms in this section.
This applies to Narang (2015) in that some countries do not experience civil war or peace at all during the observed period.
Interestingly, Narang (2015) provides this robustness test in Appendix 3, but results are neither fully reported nor discussed.
We identify a similar problem in Narang (2014). More details can be found in Appendix.
Lindner and McConnell (2018) suggest that it is because matching cannot easily distinguish between short-term fluctuations in outcomes and more structural outcome trends.
Note that the main author in Wood and Sullivan (2015) has confirmed via email that they used this specification in a working paper.
This is not a problem in both DID analyses revisited in this paper.
The interaction term’s hazard ratio is significant at 5% in column 1, suggesting that the effect of aid is different for wars with a decisive victory than the effect of aid in wars ending with a non-decisive victory. However, this result is not statistically robust across Table 2 as the interaction’s significance does not pass the 5% level in other columns (but passes the 10% level).
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The author would like to thank the editor and four anonymous referees for useful suggestions that helped improve this paper.
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Appendix
Appendix
1.1 Data sources for replication
Narang (2014): https://www.isanet.org/Publications/ISQ/Replication-Data
Wood and Sullivan (2015): https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/29076
Wood and Molfino (2016): https://www.isanet.org/Publications/JoGSS/Replication-Data
1.2 A discussion of Narang (2014)
Narang (2014) uses Cox and Weibull survival models to estimate the effect of humanitarian aid disbursements on the risk of peace failing (or the duration of peace) between 1989 and 2004. Humanitarian aid is defined as in Narang (2015). His baseline modeling specification ignores the potential endogeneity between humanitarian aid and conflict, and unobserved heterogeneity. We refer the reader to the earlier discussion on this issue. Narang (2014) first finds that humanitarian aid has no effect on the duration of peace. He includes an interaction term between humanitarian aid and a dummy variable capturing whether a war has ended with a decisive victory; the interaction term captures the possibility that the type of war settlements affects the impact of humanitarian aid. In particular, it is hypothesized that if the war ended with a decisive victory, humanitarian aid would be more likely to increase the risk of peace failing. He finds that post-conflict states treated with higher levels of humanitarian assistance exhibit shorter spells of peace, only when conflicts have ended with a decisive victory.
When re-examining Narang (2014), we identify the same issue about the interpretation of the interaction term’s hazard ratio than in Narang (2015), and, as a result, we also argue that the author ignores several results that do not support his conclusions. First, the author correctly interprets the results of Table 1 in that there is no effect of humanitarian aid on the risk of peace failing. However, the author misinterprets the results from model 1 Table 2 when the interaction term (humanitarian aid*decisive victory) is included in the Cox survival model. Narang (2014) wrongly interprets the coefficient associated with the interaction “humanitarian aid*decisive victory” (2.241) as evidence that the risk of peace failing more than doubles for every one-unit increase in the log value of humanitarian aid disbursements.
The hazard ratio for the interaction term should be interpreted as a ratio of hazard ratios. We can calculate the point estimate for the humanitarian aid hazard ratio for the case of a war that ended with a non-decisive victory (2.059), but we cannot provide information on whether the estimate is statistically significant. Given the misinterpretation of the HR in the paper, there is no apparent reason to believe that this estimate is significant. It is noteworthy to mention that this problem equally applies to other columns in Table 2.
Further, the hazard ratios for humanitarian aid are all lesser than one across Table 2, implying that humanitarian aid could lower the risk of peace failing in the case of wars that have ended with a decisive victory, but the effect across columns is statistically insignificant. As the dataset is not available for replication, we cannot provide more precise information about the statistical significance of the aid coefficient, that is, whether the effect is significant at 10%.Footnote 12
Alternately, there is another way to make use of the interaction term’s hazard ratio if one is willing to consider the interaction term’s significance at 10% (indicated by the author in the text). Table 2 in Narang (2014) implies that a war ending with a decisive victory largely decreases the risk of peace failing (as the sign of the hazard ratio associated with a decisive victory is very small and definitely lesser than one), but the positive effect of a decisive victory largely increases as humanitarian aid increases. This result is consistent across Table 2 in his paper. This original result of Narang (2014) does not support the author’s conclusions, but rather provides supportive evidence of the positive (but indirect) impact of humanitarian aid on conflict, in the case of civil wars ending with a decisive victory.
More fundamentally, the author does not provide information about the validity of the PH assumption. As the dataset is not publicly available, we cannot provide further evidence on this matter either. But given the issues highlighted in Narang (2015)’s findings based on similar Cox survival models, we suggest that these results should be taken with much caution. In sum, this discussion highlights the fact that there is little evidence that aid increases the risk of peace failing in Narang (2014). We, however, acknowledge this conclusion is conditional on the limited amount of available information (i.e. no available replication material) (Table 8).
The null assumption is that a specific year fixed effect for the treated areas is equal to the same year fixed effect for the untreated areas. For example, for the year 1999, in Wood and Sullivan (2015)’s replication, we find that we can reject the null at the 10% level.
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Mary, S. A replication note on humanitarian aid and violence. Empir Econ 62, 1465–1494 (2022). https://doi.org/10.1007/s00181-021-02064-w
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DOI: https://doi.org/10.1007/s00181-021-02064-w