# **2 Data**

## **2.1 Target variable: food crisis outbreaks**

The aim of this paper is to forecast transitions into critical states of food insecurity with enough lead time to take action. We obtain historical data on food insecurity from periodic assessments performed across 1,162 districts in 21 developing countries over the period from 2009 to 2020, obtained from FEWS NET.<sup>3</sup> Food insecurity is measured using the Integrated Phase Classification (IPC) system, an analytical framework that follows evidencebased guidelines to qualitatively classify the severity of food insecurity and prescribe policies to mitigate risk (Hillbruner and Moloney (2012) review the process). The IPC scale distinguishes five phases of food insecurity: (1) minimal, (2) stressed, (3) crisis, (4) emergency and (5) famine. Our predictions are focused on a binary “crisis indicator” defined as IPC ratings of crisis or worse, i.e. phases (3), (4), and (5). This choice is motivated by the fact that the IPC scale recommends a significant shift in policies in order to mitigate, rather than manage the risk of, severe malnutrition outcomes and death once a district enters crisis. In particular, during stressed (2) conditions and below the recommended focus is on risk management, while at crisis levels (3) and above this turns into urgent action to mitigate outcomes.

The FEWS NET data are reported at a sub-national level that follows a combination of administrative boundaries (admin2) and “livelihood zones”.<sup>4</sup> A one-on-one mapping from livelihood zones to administrative districts does not necessarily exist and the former may change over time based on expert opinions. To obtain a consistent time series, we map all the data to standard admin2 districts using a spatial overlay, assigning values to districts by majority coverage. The FEWS NET data are reported at quarterly frequency from 2009 to 2016, and then every four months afterwards. Our sample of food crisis observations used for estimation and cross-validation purposes extends through February 2019. Data for June and October 2019, and February 2020, are considered purely for temporal holdout validation. We develop predictions up to a full year ahead, through February 2020, using covariates that run through February 2019. Some of the district assessments are missing. However, our approach allows us to generate predictions for all districts where covariates are available, even if food crisis outcomes were not.

The IPC rating scale is intended to reflect the actual on-the-ground conditions inclusive of any humanitarian assistance. Since we are interested in predicting food crises themselves and not the impacts of associated humanitarian response, we need to net out the latter. Since 2012, the FEWS NET data marks locations where humanitarian assistance was significant enough to have reduced the IPC phase by one. These markers are used to reconstruct the relevant minimum IPC phases that would have been issued absent humanitarian presence. Figure A.1 in supplementary Appendix A contains the resulting data and Table 1 summarizes.

> 3FEWS NET is a leading food insecurity information provider funded by USAID that regularly publishes analysis and data on current and future food insecurity outcomes.

> 4Admin2 districts are defined by Global Administrative Unit Layers (GAUL); livelihood zones are available from FEWS NET and define sub-national geographic areas of a country, that may cut through administrative borders, in which people are assessed to share similar options for obtaining food and income and have similar access to markets.

4