communities. This led to several IDP EAs being dropped and replaced by backup EAs. Enumeration areas served as secondary sampling units and were selected with probability proportional to size, with size given by the number of blocks per EA. The required number of EAs in each IDP settlements was fixed through first‐stage sample selection. Then, where there were more or fewer than 12 blocks per IDP EA, blocks were selected with equal probability.

## _Final‐stage sample selection: Households_

Except for the special cases discussed in the previous sections, enumerators were expected to interview one household per block in all selected blocks within the enumeration area. The household was selected randomly with equal probability in two stages, following the micro‐listing protocol: From a central point in the block, the enumerator listed all residential structures within the current block into the tablet. The enumerator’s tablet then randomly selected a residential structure for the enumerator to visit. At the structure, the enumerator recorded the number of households residing in the structure, and the tablet again randomly selected a household to be interviewed.

## _Oversamples_

For Baidoa, Kismaayo, and fisheries areas, a second‐stage oversampling strategy was used. In second‐ stage oversampling, PSUs selected in the first stage and falling into the specified urban centers or coastal areas were selected again to reach the minimum sample size for each oversample. Through this process, PSUs in Kismaayo were selected twice, and PSUs in Baidoa and in fisheries areas were selected a total of three times. Fisheries livelihood zones in coastal areas were defined by FEWSNET and FSNAU (Figure A.1, zones SO7 and SO8). For the host communities oversample, all urban enumeration areas adjacent to IDP settlements were pre‐selected as a separate sampling frame. The resulting list was stratified implicitly by pre‐war region. 42 enumeration areas were selected with probability proportional to size to reach the desired oversample.

# 2.3. Sampling of the nomadic population

Nomadic households, who make up around a quarter of the Somali population according to UNFPA’s Population Estimation Survey (PESS) of 2014, are inherently difficult to sample because, by definition, they have no permanent place of residence (Kalsbeek, 1986; Soumare et al., 2007). Himelein et al. (2014) use a random geographic cluster sample approach, in which points are randomly selected from a map and all nomadic households within a radius around the point are interviewed. The SHFS followed a different approach. The strategy for sampling nomadic households relied on lists of water points used by nomadic households to water their livestock, which served as the primary sampling units. UNFPA’s 2014 PESS took a similar approach to estimate the nomadic population (UNFPA, 2014). The SHFS project deployed 200 purpose‐designed tracking devices to nomadic households who gave consent, which track their movements for two years. This will improve the understanding of the patterns of movement of the nomadic population in Somalia, which will facilitate sampling this population in the future.

## _Nomadic sampling frame_

Nomadic strata were defined at the federated member state level ( **Error! Reference source not found.** ), with the population count for each stratum provided by PESS. The list of water points was divided up by stratum. The list was put together from a combination of two sources. First, the list of water points used in PESS. Second, a regularly updated list of water points kept by the UN Food and Agriculture Organization (FAO). Given this combination of sources, the resulting list of water points used as sampling frame was 13