The main purpose of Education at a Glance is to provide an authoritative compilation of key international comparisons of education statistics. While overall values are given for countries in these comparisons, readers should not assume that countries themselves are homogeneous. The country averages include significant variations among subnational jurisdictions, much as the OECD average encompasses a variety of national experiences.
For many indicators, an OECD average is presented; for some, an OECD total is shown. The OECD average is calculated as the unweighted mean of the data values of all OECD countries2 for which data are available or can be estimated. The OECD average therefore refers to an average of data values at the level of the national systems and can be used to answer the question of how an indicator value for a given country compares with the value for a typical or average country. It does not take into account the absolute size of the education system in each country.
Data from the OECD Teaching and Learning International Survey (TALIS) present an OECD-31 average. This is the unweighted mean based on ISCED 2 teacher data across the 31 OECD countries and economies participating in TALIS with adjudicated data.
The OECD total is calculated as the weighted mean of the data values of all OECD countries3 for which data are available or can be estimated. It reflects the value for a given indicator when the OECD countries are considered as a whole. This approach is taken for the purpose of comparing, for example, expenditure charts for individual countries with those of all OECD countries for which data are available, considered as a single entity.
For tables using trend series, an additional average is calculated for countries providing data for all reference years used. This allows the OECD average to be compared over time with no distortion due to the exclusion of some countries in the different years.
For many indicators, an EU23 average is also presented. It is calculated as the unweighted mean of the data values of the 23 countries that are members of both the European Union and the OECD for which data are available or can be estimated. The present publication presents time series compiled by the OECD Secretariat for the EU23 which include the United Kingdom for the entire time series, even when data extend beyond the date of the United Kingdom’s withdrawal from the European Union on 1 February 2020. The 23 countries therefore included in this average are Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Poland, Portugal, the Slovak Republic, Slovenia, Spain, Sweden and the United Kingdom. In future publications, the “European Union” aggregate will change to exclude the UK for the entire time series.
The EU-23 total is calculated as the weighted mean of the data values of all OECD-EU countries for which data are available or can be estimated. It reflects the value for a given indicator when the OECD-EU area is considered as a whole. The coverage of countries is identical to the EU23 average.
For some indicators, a G20 average is presented. The G20 average is calculated as the unweighted mean of the data values of all G20 countries for which data are available or can be estimated (Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Korea, Mexico, the Russian Federation, Saudi Arabia, South Africa, Turkey, the United Kingdom and the United States; the European Union is the 20th member of the G20 but is not included in the calculation). The G20 average is not computed if data for both China and India are not available.
OECD, EU23 and G20 averages and totals can be significantly affected by missing data. In the case of some countries, data may not be available for specific indicators, or specific categories may not apply. Therefore, readers should keep in mind that the term “OECD/EU23/G20 average” refers to the OECD, EU23 or G20 countries included in the respective comparisons. Averages are not calculated if more than 40% of countries have missing information or have information included in other columns.
For some indicators, an average is presented. The average corresponds to the arithmetic mean of the estimates included in the table or figure.