By Pauline Rose, senior policy analyst, Global Monitoring Report team

How many children are not in school? The figure we give in the 2010 Education for All Global Monitoring Report, which has been widely picked up around the world, is 72 million. This figure was established by the UNESCO Institute of Statistics (UIS) drawing on data from ministries of education around the world. Two new reports by UIS, however, show that the actual number is likely to be much higher.

The number of children out of school is usually calculated by looking at how many children in the official primary school age range are not enrolled at school. But many countries now also consider lower secondary years an essential part of a “basic” education. The first report by UIS shows that adding children of lower secondary age would almost double the number of out-of-school children and adolescents, to 143 million.

The second report by UIS provides a detailed analysis of why estimates of school participation can differ significantly depending on whether they are calculated using data on enrolment from administrative sources or attendance data from household surveys. The study proposes many reasons for the divergences. Administrative data tend to report children’s ages according to the official primary school age rather than the children’s actual ages, and so overestimate the number of children in school at the correct age. Household surveys ask whether children are in school at some point in the school year and could also systematically miss out parts of the population most difficult to reach, so these data could also exaggerate the proportion of the population in school.

Given problems with both administrative and household data, it is not possible to determine how accurate out-of-school figures are likely to be. The overall conclusion, however, is that estimates from administrative sources, used to calculate the 72 million figure, are likely to be at the lower end of the scale. At the upper end, using household survey data rather than administrative sources, the 2010 Global Monitoring Report estimates that Ethiopia and the United Republic of Tanzania would each have more than 1.8 million additional children out of school, and Uganda over 800,000 (2010 GMR Box 2.5, pages 58-59). These numbers are significant for such countries which are generally considered to be on-track for achieving universal primary education. Globally, the 2010 GMR estimates the difference between the sources is equivalent to an increase of 30% in the total out-of-school estimate.

Getting a more accurate picture of the numbers of children out-of-school is not just a technical exercise, but a crucial step to recognising the scale of the challenge facing countries aiming to achieve Education for All over the next five years. The analysis by UIS provides an important move towards improving the reliability of information needed.