decline following the blockade. However, the results here demonstrate that in some dimensions there was a stronger impact in IPC 4 regions than in the rest of the country. Although the change in food access was very similar in IPC 4 regions and the rest of the country (columns 1 and 2), access to other basic services and the share of households with overlapping deprivations all increased by more in IPC 4 regions.<sup>41</sup> Together, these results demonstrate it could be possible that households in IPC 4 regions might have been impacted more than the rest of the country by all the different shocks that occurred during 2017.

# **7. Conclusion and Policy Implications**

We found that there was a large increase in the share of households receiving food assistance amongst the mobile phone-using population following the 2017 IPC announcement in Yemen. Furthermore, there was a small average increase in food access following the increase in the share receiving food assistance, but much of the improvement was delayed and the immediate improvement was small. We further explore potential reasons for why the improvement in food access was not stronger and more immediate.

There are two primary policy implications based on these results. First, although the results suggest that the humanitarian community is well positioned to effectively support households in the event of new conflict-related shocks, the results also suggest the potential need for more frequent updates to targeting strategies.<sup>42</sup> And second, more systematic measurement of important dimensions of well-being aside from food security can potentially help with better targeting of assistance in Yemen and future crises.

Another policy issue highlighted by this analysis is the potential need for more transparency in the measures that are pivotal in the IPC classification. As demonstrated by the summary statistics, there was little difference between much of the country based on food access measures in the survey used here. More transparency of the data used and the ways in which the evidence was used to converge to an IPC classification could be helpful in interpreting the results.

However, it is important to note that there are caveats to this analysis. In particular, the population without access to mobile phones needs to be addressed with other survey methodologies. Although face-to-face interviews that are representative of the entire population are difficult in this setting, they could at least account for some of this difficult-to-reach population. And in cases where the security situation makes it difficult to reach these households, one can complement mobile phone surveys with key informant surveys of service providers and local government officials to at least paint as complete picture as possible about the needs of the entire population in a region.

> 41Tandon and Vishwanath (2020) demonstrate that the change in access to food and basic services was very similar across the entire country. The most likely mechanism identified was a very large increase in fuel prices, which similarly was uniform across the country. In results not shown, the increase in fuel prices was similar in all IPC regions identified in the 2017 IPC announcement.

> 42As of January 2021, the next official IPC announcement following the December 2018 announcement was still being constructed. However, there have been unofficial and partial IPC updates produced for approximately one-third of the country (e.g., IPC 2019).

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