8 Total household expenditures are the same as those used to calculate the poverty rate in the countries and, where temporal and spatial deflators are available, adjusted accordingly. Annual expenditures per capita in 2022 U.S. dollars ranged from US$318 in Ethiopia to US$4,000 in Mauritius. Per capita expenditures were converted from the local currency to U.S. dollars using the official exchange rate and adjusted to 2022 U.S. dollars. As explained in annex 1, some governments maintained substantially over-valued exchange rates, making per capita expenditures much higher than those based on market-based rates. Because electricity prices are unaffected by spatial deflators and LPG prices are also unaffected in many countries, when they were used in calculations—such as comparing spending on LPG and electricity by various households—their values were not deflated. Expenditure shares were similarly calculated using un-deflated values.

Although national household expenditure surveys have the advantages mentioned in the previous section, there are limitations:

- For energy items, households are typically asked how much they had spent on a given item in the previous month or in the last 30 days or in a typical month, all of which are intended to calculate the average monthly household expenditure on the item. However, it is clear from the responses that many report how much they had paid for the last purchase or in the last month. As an illustration of the pitfalls of this approach, if a household refills an LPG cylinder every six weeks, depending on the timing of the survey, the respondent may report zero spending on LPG. A clear example of data inconsistencies arising from this type of problem is the Mexican household survey, in which the relatively large sizes of LPG cylinders and tanks commonly used in Mexico appear to result in many LPG-using households reporting zero expenditure in the previous month. For example, in the 2008 survey, 80 percent of households reported that LPG was their primary cooking fuel but only 60 percent had reported non-zero expenditures because they were asked to tell the enumerator how much they had spent on LPG in the previous month (Kojima, Bacon, and Zhou 2011). Conversely, a household that purchases LPG less frequently than once a month but happened to have had purchased LPG in the preceding month might report the full purchase amount, over-stating how much the household spends on LPG on average every month.

- Expenditures on consumed goods and services obtained free of charge, such as wood or dung gathered by households, are usually imputed “market” values but how systematically they are recorded and valued is unclear. In the extreme, in areas where firewood is virtually universally collected and there is no market for it, assigning a market value would be challenging. In addition, while households may recall how much they had spent purchasing wood in the last 30 days, those collecting wood would need to estimate the quantity, which would be multiplied by the proxy market price. Doing so accurately would be extremely challenging even under the best of circumstances.

- Apart from asking about primary sources of energy for cooking and lighting, questions about end-use are typically not asked. Even when primary sources are known, they may be used for other purposes. For example, if a household cites kerosene as the primary source of energy only for lighting, it does not follow that kerosene is never used for cooking. Particularly problematic are gasoline and diesel, which may be used as automotive fuels in vehicles or fuels in electricity generators, and if the latter, electricity so generated could be used for cooking. Unless their uses are distinguished in the survey questionnaire, which they are usually not, it is not possible to tell how they were used by households reporting non-zero expenditures on either of these fuels and hence they are included in Figure 4.