# **II. Data and methodology**

This study draws on data from the DHS conducted in Sub-Saharan African countries with at least two rounds of data.<sup>5,6</sup> The sample consists of 21 countries observed at two points in time, resulting in a total of 42 country-year datasets. This set of countries encompasses 52 percent of the population of Sub-Saharan Africa (World Bank 2007).

The earliest data are from 1991 in Cameroon while the most recent data used are from 2006 in Niger and Uganda. All surveys were conducted using a standardized questionnaire and aim to be nationally representative of the non-institutionalized civilian population.<sup>7</sup> The countries range from low-HIV prevalence countries—nine out of 21 countries have HIV prevalence below 3 percent—to countries with very high prevalence levels—Malawi (14 percent), Namibia (20 percent), Zambia (17 percent) and Zimbabwe (20 percent).<sup>8</sup> The sample sizes range from just above 10,000 children under 15 in Cote d'Ivoire in 1994 to almost 33,000 in Mali 2001—the median across all surveys is about 18,000 children under 15. It is important to note that for each country, the earliest and latest survey years available are used and that the number of years between the two surveys varies across countries—from a minimum of five years in three of the countries (Benin, Ethiopia and Rwanda) to 14 years in Niger. The median gap between the earliest and latest years is 10 years. Survey years and sample sizes, as well as HIV prevalence estimates, are reported in the Annex Table. For some countries, more than two surveys are available, although these interim rounds are not used.

An orphan is defined as a child under the age of 15 for whom one or both parents are reported to be deceased. The age-threshold is based on the structure of the DHS questionnaire in most of the countries. Single orphans are those who have only one surviving parent. A maternal

> 5 See UNICEF (2006) for a discussion of the validity of household survey sample frames for capturing a “true picture of all orphaned and vulnerable children living in a community.” The report concludes that national-level indicators on children orphaned and made vulnerable by HIV and AIDS can be obtained through household-only surveys—data do not need to be collected from children living in institutions or outside of households (e.g. as street children).

> 6 Several countries, including the Republic of Congo, Gabon, South Africa, and the CAR, were excluded because only a single survey was available at the time of data analysis. Several datasets, including Burkina Faso 1998/99, Cote d’Ivoire 1998/99 and Senegal 1997 had to be excluded due to missing information on parental survival status. 7 In all the analyses undertaken, survey sampling weights as provided in the DHS data are used in order to maintain this representation.

> 8 The HIV prevalence estimates cited are drawn from the UNAIDS (2006). These estimates are based on country surveillance systems and, where available, population-based surveys with HIV testing. Comparisons between surveillance system and population-based estimates suggest that the former tend to overstate prevalence.

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