Not all the countries have full information on enrolment or on the parameters
involved in (A.1). In several cases, especially in African countries, population data is
very limited and available only back as far as 1950. In these cases, it is assumed that
net intake rates before 1950 were the same as in that year. While this assumption may
appear unrealistic, it is unlikely to produce major errors because, as the data shows,
enrolment and net intake rates were very low in 1950 and close to zero in secondary
and higher education. Thus the error will be limited to (the very low) participation in
primary education