worst-off households during active conflict is most effective in staving off the adverse outcomes associated with lifelong impacts (e.g., Kurdi et al. 2019). However, the lack of updating despite significant changes in both food security and conflict in the country suggests that official early warning systems need to be updated more regularly.

Second, the lack of a stronger and more immediate improvement in food access suggests potential improvements to data collection during humanitarian crises. In addition to monitoring traditional metrics that focus wholly on food access, capturing important categories of non-food consumption and access to basic services in high-frequency surveys could help to better understand how in-kind food assistance, cash transfers, and other types of humanitarian assistance might impact household wellbeing during humanitarian crises. In many crises, including in Yemen’s, food is one of many urgent needs (e.g., OCHA 2017). Although it has long been recognized that the impacts of in-kind assistance might not increase consumption of the goods being provided to beneficiaries (e.g., Behrman and Deolalikar 1989, Jensen and Miller 2011, etc.), it is possible that the existence of many overlapping and potentially competing deprivations could make the situation more likely. Although some assessments, such as the 2017 IPC announcement, do take a wide variety of indicators into account and captures some of these other urgent needs (e.g., Maxwell et al. 2020), more systematic measurement of other important dimensions can potentially help with better targeting of assistance in Yemen and future crises.

The rest of the paper is organized as follows. Section 2 discusses the official 2017 IPC announcement in Yemen; section 3 discusses the data; section 4 presents important summary statistics of food assistance and food access; section 5 presents the empirical strategy and how food assistance and food access changed following the 2017 IPC announcement; section 6 discusses potential reasons why the increase in the share of households receiving assistance might not have had a larger or more immediate impact on food access; and section 7 concludes.

# **2. The 2017 Integrated Food Security and Phase Classification in Yemen**

The official 2017 Integrated Food Security and Phase Classification (IPC) was released in March 2017 by the Yemen IPC Technical Working Group. The announcement classified each governorate and the municipality of the capital- 22 regions in total- on the IPC scale, which is a system that has been adopted by the United Nations and their humanitarian partners to identify food emergencies. To determine the classification, the technical committee combined information on food security, nutrition, and other indicators to best identify each region of the country on the IPC scale (IPC 2017).

The classification differentiates between five progressively worse food insecurity phases- generally food secure (IPC 1), borderline food insecure (IPC 2), acute food and livelihood crisis (IPC 3), humanitarian emergency (IPC 4), and famine/humanitarian crisis (IPC 5). The classifications respectively correspond to more than 80 percent of households can meet their food needs in absence of coping strategies, at least 20 percent of households have consumption that is lessened but still adequate, at least 20 percent of households have significant intake shortfalls that cannot be met without irreversible coping strategies, at least 20 percent of households have 4