Sample Design

Each participating country designed a sample to be representative of its civilian, non-institutionalized population, age 16 to 65. In the United States, a stratified multi-stage probability sample design was employed.

A sample size of 5,400 completed cases in each official language was recommended for each country that was implementing the full ALL assessment. A sample size of 3,420 complete cases in each official language was recommended if the Problem Solving domain was excluded from the ALL assessment. The United States did not implement the Problem Solving domain and had a final sample size of 3,420.