Technical annex Data sources Calculation of current global figures UNICEF global databases include birth registration estimates for 174 countries, primarily drawn from nationally representative household surveys such as the Multiple Indicator Cluster Surveys (MICS) and Demographic and Health Surveys (DHS). Other data sources in the global database include other national surveys, censuses and vital statistics from civil registration systems. Of the 174 countries with data, 163 have estimates that are recent enough (2010 to 2018) to be included in the calculation of current global and regional levels. (For a summary of data availability by region and by indicator, see table below). Maps only include the latest available data point for each country between 2010 and 2018. Global estimates of birth registration for children under age 5 and under age 1 are calculated based on the following: (1) latest available data for each country, within the period 2010 to 2018, (2) estimated coverage of birth registration for 30 countries in Western Europe, 2 in North America and an additional 24 countries with no comparable data in the UNICEF global database made on the basis of the information obtained from UNSD on estimated coverage of birth registration within national civil registration systems, and (3) proxy indicator of hukou registration for China. For countries without an available data source, information on the estimated coverage of birth registration within national civil registration systems was obtained from the United Nations Statistics Division (UNSD). This was the case for 30 countries in Western Europe and 2 in North America as well as an additional 24 countries in other regions. Several sources are used by UNSD to obtain coverage of birth and death registration for more than 230 countries and areas. The primary source is the ‘Quality of vital statistics obtained from civil registration’ page on the United Nations Demographic Yearbook Vital Statistics Questionnaire completed by national statistical offices. Other sources include UNSD workshops that have been conducted in the past, when coverage information was obtained from country representative(s) either from the national statistical office or the civil registration authority. For more information, visit <unstats.un.org/unsd/demographic-social/crvs/#coverage>. For China, internationally comparable and nationally representative data on birth registration prevalence have not been available historically. However, data are available for a related indicator on registration of children’s permanent residence, known as ‘hukou’, by the household registration department. Hukou registration is the only indication that birth registration has been carried out and completed, and hukou registration is one of the most important components of the household management system in China. The latest available data on children’s hukou registration were obtained from the National Population Sample Survey (also referred to as a ‘mini-census’) conducted in 2015 by the National Bureau of Statistics of China. Demographic data are from the United Nations, Department of Economic and Social Affairs, Population Division, World Population Prospects 2019, Online edition, Revision 1. 36 Birth Registration for Every Child by 2030: Are we on track? Global estimates of possession of a birth certificate for children under age 5 and under age 1 are calculated based on the following: (1) latest available data for each country, within the period 2010 to 2018, and (2) for the 30 countries in Western Europe and 2 in North America, an assumption was made that all children have birth certificates on the basis of the information obtained from UNSD on estimated coverage of birth registration within national civil registration systems. For this set of estimates, no additional assumptions are made for other countries on possession of a birth certificate. Global figures are calculated as a population-weighted average of the prevalence of birth registration in each of the regions used for UNICEF global reporting (see page 40). The prevalence of birth registration (or certification) is subtracted from 100 to obtain the prevalence of children without birth registration (or without a birth certificate). Absolute numbers of unregistered children are calculated by applying the resulting prevalence of children without birth registration (or without a birth certificate) to the respective child population (either those under age 5 or under age 1). Calculation of current regional figures Each regional prevalence is calculated as a populationweighted average of the national values. In using this method, the prevalence in countries without data is implicitly assumed to be the same as the population-weighted average of other countries in the same region. Regional estimates are presented according to the regional classification used for UNICEF global reporting. Regional estimates are presented even when the population coverage falls below the standard threshold of 50 per cent, but are noted accordingly throughout the report. The same set of methods and assumptions as those outlined above for calculation of global figures of overall birth registration and possession of a birth certificate applies to the calculation of regional figures.