But education is not, by itself, a satisfactory or simple proxy for literacy. Thus, comparisons based solely on educational attainment may incorrectly estimate true skill differences. While there is a relationship between parent education and tested literacy, that relationship is not the same in all cases. It is also worthwhile noting that the IALS countries are quite varied in parents' education. Age Education is not only distributed differently among the countries, but it is also distributed differently by age within each country.
Literacy is related to age independently of education as well.
The relationship between age and literacy is slightly more complex than the relationship between education and literacy. In all countries except the United States, at older ages, the proportion at Level 1 is larger on all three scales. The mixed results seen in these data demonstrate that adult literacy is a result not just of school experience, but also of life experience. This implies that the IALS results are not an appropriate measure of school effectiveness, but rather a measure of the culture of literacy in a particular society. It is safe to say that in all countries the proportion of young adults who will be entering the work-force, on average, have notably higher skill levels than older workers who will be retiring.