Methodology

The Inter-agency Group for Child Mortality Estimation is made up of UNICEF, WHO, The World Bank and United Nations Population Division. This group generates yearly estimates based on the methodology described below.

Definition of the indicator

The under-five mortality rate is the probability (expressed as a rate per 1,000 live births) of a child born in a specified year dying before reaching the age of five if subject to current age-specific mortality rates.

Methods of computation

The under-five mortality rate can be calculated using methodologies that depend on the type of data available. In practice, data can be obtained from registration of births and deaths via vital registration systems, data from national population census and/or data collected via household surveys. When data collected via vital registration systems is of good quality, the under-five mortality rate can be easily estimated by observing the survival status of different cohorts along time and to specific ages since the moment of birth. Under-five mortality rate can be derived from household survey data using direct or indirect methods. The direct method uses data collected on birth histories of women of childbearing age and produces the probability of dying before age five from children born alive, among women of childbearing age, during five year periods before the survey (0-4, 5-9, etc.). The indirect method uses the Brass method which converts the proportion dead of children ever born reported by women in age groups 15-19, 20-24,…., 45-49 into estimates of probability of dying before attaining certain exact childhood ages.

Process for obtaining data and estimation

UNICEF compiles under-five mortality rate country estimates derived from all sources and methods of estimation obtained either from standard reports, direct estimation from micro data sets, or from UNICEF's yearly exercise, CRING^*. In order to sort out differences between estimates produced from different sources, with different methods, UNICEF developed, in coordination with the World Health Organization, The World Bank and United Nations Population Division, an estimation methodology that minimizes the errors embodied on each estimate and harmonizes trends along time. Since the estimates are not necessarily the exact values used as input for the model, they are often not recognized as the official under-five mortality rate estimates used at the country level. However, as mentioned before, these estimates minimize errors and maximize the consistency of trends along time.

Data availability including timing

Vital registration data is available on a yearly basis but often is published at the country level with a lag of 2 or more years. Unfortunately, vital statistics are unreliable in most developing countries. Population censuses are regularly conducted every ten years and results are published within 1-3 years after the population count. Households surveys, such as DHS and MICS, are in general implemented every 3-5 years with results published within a year of field data collection. It is important to mention that in average, the most recent under-five mortality rate estimates from household surveys refer to 2.5 years before the time of the survey or 3.5 years at the moment of publication of findings.

Under-five mortality rate estimates from the Inter-agency Group for Child Mortality Estimation (IGME) refer to the year before the year the respective agency publishes (in the case of UNICEF for example, the 2006 State of the World's Children report published in November 2005 includes under-five mortality rate estimates corresponding to the year 2004). Recent estimates are consistent with the trend observed during the last 30 years.

Treatment of "missing" values

The most recent under-five mortality rate estimates produced by the IGME are extrapolation of observed trends obtained from observed under-five mortality rate values derived from different data sources and methods.

Regional and global estimates

Under-five mortality rate estimates are produced and presented by region and globally only if data is available for at least 50% of the region or the total population of the countries considered. Estimates are not included if this rule is not accomplished.

Comments and limitations (data quality)

In the majority of developing countries, under-five mortality rate estimates are obtained from household surveys and therefore have attached confidence intervals that need to be considered when comparing values along time or across countries. Similarly, these estimates are often affected by non-sampling errors that may affect equally recent levels and trends of under-five mortality rate. Click on the links to access An Assessment of the Credibility of Child Mortality Declines Estimated from DHS Mortality Rates and Comparison of spline- and loess-based approaches for the estimation of child mortality.

Key references