In each country participating in PIAAC a probability-based random sample will be selected. The PIAAC target population comprises the adult population of a country between the ages of 16 and 65 regardless of nationality or residential status. It does not include those who live in institutionalized group quarters, for example in nursing homes or prisons.
Approximately 5,000 randomly selected adults between the ages of 16 and 65 will be interviewed in each participating country.
In Germany, a registry-based, two-stage sampling procedure will be implemented. At the first stage, a sample of municipalities will be drawn from the entire federal territory using the latest edition of the Federal Statistical Office's directory of municipalities. This will result in a random sample of municipalities. At the second stage, in each selected municipality target persons will be randomly selected from the register of residents.
According to international standards a response rate target of 70% has to be achieved. However, a minimal response rate of 50% is regarded as acceptable for a country to be included in the international data base if it can provide evidence that the realized sample is not or only marginally biased.