# 4. Data

This study is based on data of four waves of the Nigerian General Household Panel<sup>14</sup> Survey (GHS 1 – 2010/2011; GHS2 – 2012/2013; GHS3 – 2015/2016; GHS4 – 2018/2019), and one wave of the Nigerian Multiple Indicator Cluster Survey (MICS 5 – 2016/2017). The GHS surveys have been conducted by the Nigerian National Bureau of Statistic in collaboration with the World Bank’s Living Standard Measurement Study (LSMS) team. Each wave covers close to 5,000 households and consists of two visits covering different survey modules; one post-planting and another post-harvest season to account for seasonal variation. The monetary poverty analysis relies on the household roster of the post-harvest visit and the per capita consumption aggregate values.<sup>15</sup> For the multi-dimensional poverty analysis this study complements the post-harvest modules with those from the post-planting survey (see footnote).<sup>16</sup> The MICS covers close to 34,000 households and was conducted by the Nigerian National Bureau of Statistics together with UNICEF<sup>17</sup> . Estimates based on both surveys are presented in weighted form.

While both surveys are nationally representative, the GHS is only representative up to the regional level whereas the MICS is representative at the state level. Even though Nigeria is a very heterogeneous, country that may suggest advantages of using surveys representative at the state level, there are important benefits of also using the GHS survey data for this analysis. Though only representative at the regional level, the GHS surveys allow a comparison of the overlap of monetary poverty and multidimensional poverty in terms of deprivations and provide evidence on the time trend. The MICS, though representative at the state level, allows only the calculation of deprivation levels, as it does not include information to infer about monetary poverty.

> 14 Though a panel survey, the data can be used as an individual level panel across visits within a wave, but only as a household level panel across waves. The GHS wave 4 sample only includes a subset of the earlier waves’ sample households in addition to a refresh sample. (For a discussion see NBS and World Bank (2019).). Though a representative long panel is kept in wave 4, the part of the analysis relying on panel data, only uses data up until wave 3 as sample sizes in the long panel up until wave 4 are considered too small for the purpose of this analysis.

> 15 Due to the unbalanced nature of the panel and household members joining and leaving the household between post-planting and post-harvest, thus leading to slightly different household sizes, whereas the mean per capita consumption figure of the household remains constant, results in slightly different individual level post-planting versus post-harvest poverty rates. Hence, these also slightly differ from the aggregate poverty rates based on household level data.

> 16Health deprivation can only be estimated from waves 1 and 2, as the survey module is missing in waves 3 and 4. Education deprivation is based on the education module in the post-planting surveys in waves 1 and 2 and the post-harvest survey in waves 3 ad 4. For information deprivation household asset ownership data, only available in the post-planting survey, is assumed to be a proxy for access to these assets. While an access question exists, in wave 3, tv and radio access questions were dropped, so that this not allow consistent comparisons. Thus, household ownership of these assets was chosen to be a good proxy. Charity and tanker water were assumed to be protected, but not directly drinkable water sources. Drinking water source, sanitation and shelter data was in waves 1 and 2 only available in the post-harvest surveys and in wave 3 and 4 only in the post-planting survey. 17 Information concerning Education and current school enrollment deprivations is taken from the household roster and supplemented by information provided in the men and women surveys.

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