Divide the number of students attending a given level of education regardless of age by the population of the age group which officially corresponds to the given level of education.
Data from household surveys on school attendance for a given level of education.
A high GAR generally indicates a high degree of attendance, whether the students belong to the official age group or not.
In the case of primary and secondary education, a GAR value approaching or exceeding 100% indicates that a country is, in principle, able to accommodate all of its school-age population, but it does not indicate the proportion already attending. The achievement of a GAR of 100% is therefore a necessary but not sufficient condition for attending all eligible children in school. When the GAR exceeds 90% for a particular level of education, the aggregate number of places for students is approaching the number required for universal access of the official age group. However, this is a meaningful interpretation only if one can expect the under-aged and over-aged attendance to decline in the future to free places for pupils from the expected age group.
The GAR will in theory be an underestimate if a household survey only collects data on current school attendance up to a certain age, e.g. 24 years. In this case, the survey contains no information on students above 24 years of age and they will therefore be excluded from the numerator during calculation of the GAR.
In cases where household surveys do not make it possible to distinguish clearly between post-secondary non-tertiary education (ISCED 4) and tertiary education (ISCED 5-8), students in post-secondary non-tertiary education may be mistakenly counted as attending tertiary education and the GAR can therefore be overestimated.
The GAR can exceed 100% due to the inclusion of over-aged and under-aged students. Reasons include early or late entry, and grade repetition. For tertiary education, the GAR can exceed 100% due to the inclusion of students outside the 5-year age group starting from the official secondary school graduation age. A rigorous interpretation of the GAR needs additional information to assess the extent of repetition, late entry, etc.
Treatment of missing data: All observations with missing information on age, whether the student is currently attending school, and the current education level attended, are omitted from the calculation of education indicators.
School participation in household surveys and population censuses is commonly measured by whether students attended a given grade or level of education during the academic reference year. Therefore, indicators of school participation derived from household survey data refer to attendance. The GAR can also be a complementary indicator to the net attendance rate (NAR) by indicating the extent of over-aged and under-aged attendance.
The GAR is calculated with data from international household survey programmes, such as the Demographic and Health Surveys (DHS) and the Multiple Indicator Cluster Surveys (MICS), national surveys or population censuses.
ISCED recalculation of household survey data for education indicators. The age ranges associated with the education levels are based on the International Standard Classification of Education (ISCED). The education levels and grades used in the calculation of education indicators are consistent with each country’s ISCED mapping.
Age data methodology: The data collection period for international household survey programmes like the DHS and MICS may not be aligned with the academic year. This can create distortions in the age data used to calculate education indicators. Education systems generally define the intended or “official” ages for a given level of education based on the age of a student at the beginning of the academic year. In other words, the reference date for ages is the start month of the academic year.
By contrast, household surveys may collect data on the educational status and age of children many months after the start of the school year. The reference date for age information is the date the survey data were collected, which means it varies among households. Considering the gap between the start of the school year for which attendance data are collected and the date on which the survey was carried out is crucial for accurate calculation of education indicators. To minimize the associated error, the UIS takes different measures depending on the number of months between the start of the academic reference year and the time of survey data collection.
• Where information is available on the birth month and year of school-age children, age data are recoded to the age at the start of the academic reference year.
• If only the age in years is available, and data for the majority of observations were collected 6 or more months after the start of the school year, one full year is subtracted from the age recorded during data collection (adjusted age = recorded age – 1). For example, if the school year starts on 1 September and data for the majority of observations were collected in March of the following year or later, the ages will be adjusted.
• If only the age in years is available, and data for the majority of observations were collected 5 months or less after the start of the school year, age data are used as recorded. For example, if the school year starts on 1 September and data for the majority of observations were collected during the period up to February of the following year, the recorded ages are used without adjustment.
Data from household surveys are usually disaggregated by sex, location and household wealth quintile. The location (urban or rural) is defined according to national standards, which may differ across countries. Household wealth quintiles are usually determined with the help of an asset index, calculated from assets owned by individual households (housing material, water and sanitation, appliances, vehicles, livestock, etc.).
Number of students attending a given level of education at any time during the reference academic year, regardless of age, expressed as a percentage of the official school-age population corresponding to the same level of education. For the tertiary level, the population used is the 5-year age group starting from the official secondary school graduation age.