*2.2. Participant Selection, Data Collection and Analysis*

The selected households had SHS products with ratings of 12 Watts-peak (Wp) in FCT, and 50 Wp in Lagos State, both of which possess 4 LED lighting points and providing lighting service for at least 6 h a day. They also powered a small radio, charged mobile phones and LED torchlights, while the higher capacity systems in Lagos State were connected to a DC-powered television with the ability to pick up selected satellite broadcasts. At the time the interviews were held, the households had owned their SHSs between 6 months and 4 years, with a median ownership period of 29 months. The households made monthly PAYG payments for accessing the SHS via an authorised agent.

Data collection was via face-to-face interviews and respondents (one per household, usually the household head unless unavailable) were first asked basic demographic-type questions, and due to the seasonal nature of their occupation (mostly farmers and fishermen), they were not asked about their income; instead the researchers used the numbers of household members, size of the house, i.e., number of rooms, and the amount spent on non-cooking energy purchases, as proxy indicators for wealth. Respondents were then asked about their non-cooking energy mix, including their current expenditure patterns and willingness to pay for grid electricity. They were also asked about the electrical appliances already owned by the household, and the appliances they desired to own. The survey questionnaire is included in Appendix A.

**Figure 3.** Map of Nigeria showing the states and local government areas (LGA) where the energy surveys were performed. Note that the FCT does not have LGAs, but instead is made up of Area Councils, of which Gwagwalada is one.


**Table 1.** Communities selected for the survey along with the number of households (HH) in each community.

The questions were mostly 'closed' in nature where respondents were provided with a series of options and asked to tick the ones which applied to them. The options provided to the respondents were based in part on published research designed to explore energy use by rural households but also on a series of interviews held with key informants in both Lagos and FCT. There were a few open-ended questions to allow the respondents to provide answers in their own words rather than select from a range of options. In both locations, research assistants familiar with the local languages were recruited to help with the interviewing, as many of the respondents did not understand, or speak English. The questionnaire was written in English and the research assistants verbally translated the questions into the local languages in situations where the respondents did not understand English. While translation between languages risked introducing errors in the results, the structured nature of the questionnaire (which, other than 3 open-ended questions, consisted of closed questions and predefined answers), mitigated this risk.

Data analysis was performed using both quantitative and qualitative methods. The approach to the analysis of the qualitative data was a deductive one and thematic analysis method was used in analysing the data, with the transcription and coding of the interviews performed in Microsoft Word and Nvivo 12, respectively. The quantitative data were analysed using a mixture of descriptive and inferential statistics. As the quantitative data comprised counts of responses, analysis was undertaken using non-parametric statistical tests to explore associations between categories. The Chi-square test was used to determine whether potential associations between different variables were in fact significant. In cases where at least 80% of the expected frequencies of the data are less than 5, the Fisher's exact test was used instead. For post hoc testing, the odds ratio (for 2 × 2 tables) method was used, while the adjusted standardized residual method proposed by Agresti [39] was used for all other tables. The software Statistical Package for the Social Sciences (SPSS) was used to perform the statistical analyses. The statistical tests for FCT and Lagos State households were performed separately and are presented in the subsequent tables.

All interviewed participants gave their informed consent for inclusion before they participated in the study. The data collection protocol involving human subjects was vetted and approved by the University Ethics Committee (UEC) of the University of Surrey (UEC ref: UEC 2018 039 FEPS).
