9 The procedure for aggregating consumption in each country was that followed to examine the poverty rate. Per capita expenditures were computed by dividing household expenditures by household size. Population weights were used to classify the entire population into five expenditure quintiles with the same number of people in each quintile. The bottom quintile, or quintile 1, had the lowest expenditure per capita and the top quintile, or quintile 5, had the highest expenditure per capita. Because the household size on average decreases with increasing wealth, the _number of households_ increased with increasing quintile. The quintiles were further segregated into urban and rural. The lower quintiles had many more rural households while urban households tended to be in upper quintiles. In Mauritius, the publicly available survey data sets did not contain information on the split between urban and rural, and hence only national results are presented. Universal access is generally measured by population and not households, including for the purpose of tracking SDG 7, and hence the results in this paper related to access are expressed as percentages of people rather than households. Because household representatives answer questions about household use of energy, the phrase used is “people living in households citing [or using]” a specific form of energy.

For the purpose of computing the share of total household expenditures spent on different forms of energy, outliers—defined as those spending more than 30 percent of total expenditures on any form of energy—were excluded to avoid having them dominate the results. All surveys enabled calculations of total household expenditures, taken as a proxy for income to leading order, with the exception of the South African survey, which asked households to choose one of the 10 income brackets. As a result, expenditure quintiles could not be computed for South Africa. Outlier households were not excluded in all other calculations, such as the number of people citing different forms of primary energy for cooking or those who had abandoned the use of polluting fuels.

One challenge in interpreting the expenditures is that freely acquired goods—the largest proportion of which is food, especially in rural areas, but solid biomass may also be collected free of cash—are included, making total expenditures less representative of income for those households where a material fraction of total expenditures is imputed. Modern commercial energy requires cash outlays, and the ability to pay for LPG or electricity is a function of both income and the needs that are met through cash-free acquisition, making neither total household expenditures as calculated nor cash-only expenditures fully satisfactory for the purpose of assessing the ability to pay. Further, many households do not distinguish how a given good was acquired, especially different forms of energy, and hence calculating cash expenditures consistently across the countries surveyed was not possible.

This study classifies kerosene, wood, charcoal, coal, dung, agricultural residues, other solid fuels, and energy characterized as “other” in the survey questionnaire as polluting fuels. While wood may have included compressed pellets burned in advanced-combustion stoves (Kojima 2021b), such occurrences would have been extremely rare in Sub-Saharan Africa during the survey period and their exclusion would not have materially distorted the results. A household was considered to have had abandoned polluting fuels if the household did not name a polluting fuel as the primary cooking fuel and reported zero expenditures on all polluting fuels. Abandonment so measured signals abandonment of all polluting fuels by the household for all household activities and not just for cooking.

Abandonment of polluting fuels following LPG adoption was examined by confining the samples to those areas where there were enough households using LPG as their primary cooking fuel. Because the sample size varied from fewer than 4,000 in Eswatini and Niger to slightly more than 20,000 in three countries, the cut-off point of 20 percent was chosen as the selection criterion for examination of abandonment— intended to strike a balance between coverage (having enough countries for analysis) and significance (obtaining representative results)—and only those areas where 20 percent or more of the population cited