Programme for International Student Assessment 2009

The specific sample design and size for each country aimed to maximise sampling efficiency for student-level estimates. In OECD countries, sample sizes ranged from 4,410 students in Iceland to 38,250 students in Mexico. Countries with large samples have often implemented PISA both at national and regional/state levels (e.g. Australia, Belgium, Canada, Italy, Mexico, Spain, Switzerland and the United Kingdom). The selection of samples was monitored internationally and adhered to rigorous standards for the participation rate, both among schools selected by the international contractor and among students within these schools, to ensure that the PISA results reflect the skills of the 15-year-old students in participating countries. Countries were also required to administer the test to students in identical ways to ensure that students receive the same information prior to and during the assessment.

When a school has been selected to participate in PISA, a school co-ordinator is appointed. The school coordinator compiles a list of all 15-year-olds in the school and sends this list to the PISA National Centre in the country, which randomly selects 35 students to participate. The school co-ordinator then contacts the students who have been selected for the sample and obtains the necessary permissions from parents. The testing session is usually conducted by a test administrator who is trained and employed by the National Centre. The test administrator contacts the school co-ordinator to schedule administration of the assessment. The school coordinator ensures that the students attend the testing sessions. This can sometimes be difficult because students may come from different grades and different classes. The test administrator's primary tasks are to ensure that each test booklet is distributed to the correct student and to introduce the tests to the students. After the test is over, the test administrator collects the test booklets and sends them to the National Centre for coding.

In PISA 2009, 13 different test booklets were used in each country. Each booklet had a different subset of PISA questions, so that students answered overlapping groups of questions, in order to produce a wide range of test items while limiting the test time for each student. With 13 different booklets, in each group of 35 students, no more than 3 students were given the same booklet. Booklets were allocated to individual students according to a random selection process. The test administrator's introduction came from a prescribed text so that all students in different schools and countries received exactly the same instructions. Before starting the test, the students were asked to do a practice question from their booklets. The testing session was divided into two parts: the two-hour-long test to assess their knowledge and skills, and the questionnaire session to collect data on their personal background, their learning habits, their attitudes towards reading, and their engagement and motivation. The length of the questionnaire session varied across countries, depending on the options chosen for inclusion, but generally was about 30 minutes. Students were usually given a short break half-way through the test and again before they did the questionnaire.

For more information on PISA's technical background, refer to the documents "PISA 2009 Results: Overcoming Social Background - Volume II", Annex A and "PISA 2009 Technical Report" that are provided as external resources.