The harvest quantity on each plot was then valued using a set of constant crop prices. Specifically, each price corresponds to the median crop sale price calculated in one survey round in each country. Applying constant prices for each crop-country combination eliminates the effect of relative price fluctuations over time. This allows us to isolate the impact of disasters on harvest quantity rather than measuring their impact on quantity _and_ prices. An alternative approach was used to calculate and report aggregate losses, such as in Table 4 and Figure 3. In these cases, country and wave specific prices were calculated, by estimating median farmer sale prices for different crop types. This was done to reflect losses as they were perceived by farmers in the year of the shock. Whether current or constant, harvest values are initially calculated in local currency units and then converted and adjusted to 2020 USD using exchange rates and a CPI drawn from a library of the World Bank World Development Indicators.<sup>53</sup> Yields, defined as the value of production per hectare, were obtained by dividing the total harvest value on the plot by GPS-measured plot area. Finally, yields are winsorized at the 1<sup>st</sup> and 99<sup>th</sup> percentiles (while allowing full losses to be equal to 0).

# _Identification of disaster events and loss size_

Identification of disaster events is based on farmers reporting crop production losses before harvest for each crop on each of their plots. Specifically, for each crop cultivated on each plot, farmers are asked whether the area harvested was less than the area planted, i.e. if some of their crop has been lost, along with the cause of the loss in harvested area. In Ethiopia, farmers are further asked whether the crops they harvested had any damage on them and what the cause of damage was. We define disaster crop losses as any loss in crop area or any damage on the crops harvested due to climatological (drought, irregular rain, hail, wildfire), hydrological (flood) or biological (insect infestation, disease) reasons. This does not include losses due conflict, unavailability of inputs or other household or socio-economic events. We denote a plot with a disaster loss as any plot for which at least one crop on the plot had a disaster-induced loss.

To calculate the size of disaster losses, we use farmers’ reports of the share of the planted area lost due to disasters and, where available, the percent of damage on crops that were harvested. To determine the potential harvest that could have been achieved in the absence of disaster losses, we employ the methodology proposed by the Food and Agriculture Organization (FAO).<sup>54,55</sup> This means determining the realized harvest for each crop on the plot, as described in the preceding section, and scaling it up in proportion to the planted area lost and degree of damage on the crop that is attributed to disasters. The quantity lost equates to the difference between the potential harvest without disaster losses and the realized harvest. To aggregate losses across crops, we value loss quantity of each crop on each plot using a constant set of prices, which we then convert to 2020 US dollars. In order to correct for outliers in the self-reported data, we winsorize these loss values at the 99<sup>th</sup> percentile.

Equation (1) formalizes the construction of the plot-level loss aggregate.

12