ICCS 2009 Technical Report - IEA

Populations and samplesThe ICCS student population comprised students in Grade 8 (i.e., students who, on average, areapproximately 14 years of age), provided that the average age of students in this grade at thetime of testing was 13.5 years or above.The samples were designed as two-stage cluster samples. In the first stage of sampling, schoolswere sampled within each country using PPS (probability proportional to size as measured bythe number of students enrolled in a school). The numbers required in the sample to achievethe necessary precision were estimated on the basis of national characteristics. However, asa guide, a minimum sample size of 150 schools was planned in each country. Within eachsampled school, an intact class from the target grade was sampled randomly, and all students inthat class were surveyed.The population for the ICCS teacher survey was defined as all teachers teaching regular schoolsubjects to the students in the target grade (mostly Grade 8) at each sampled school. Up to 15teachers were selected at random from all teachers teaching the target grade at each sampledschool. In schools with 20 or fewer such teachers, all teachers were invited to participate. Inschools with more than 20 teachers, 15 of those teachers were sampled at random.Outline of this reportThis report is structured so as to provide technical detail about each aspect of ICCS. Thisoverview is followed by a series of chapters that provide detail about different aspects of ICCS.Chapters, 2, 3, 4, and 5 are concerned with the instruments. Chapter 2 provides informationabout the development and properties of the ICCS cognitive test. Chapter 3 details thedevelopment and properties of the ICCS international questionnaires. These include theinternational student questionnaire, the teacher questionnaire, and the school questionnaire,as well as the national contexts survey. Chapter 4 is concerned with the development of theICCS regional instruments: the European test and questionnaire, the Latin American test andquestionnaire, and the Asian questionnaire. Chapter 5 describes the procedures used to translateand adapt ICCS instruments.Chapters 6 and 7 are concerned with aspects of sampling. Chapter 6 details the samplingdesign and implementation and Chapter 7 documents the weighting procedures that were usedto ensure the results from ICCS represented the defined populations in each country.Chapters 8, 9, and 10 focus on the survey implementation. Chapter 8 details the field operationprocedures and the process of preparation of data files. Chapter 9 documents the quality controlprotocols and procedures that were used in the ICCS data collection. Chapter 10 provides anaccount of data management in ICCS and the creation of the ICCS database.Chapters 11, 12, and 13 describe the psychometric and statistical analyses used in ICCS.Chapter 11 reports on the scaling procedures for the ICCS cognitive test and how responsesto the test items were used to construct scores on the ICCS civic knowledge scale. Chapter 12describes the methods used to form scales from the ICCS questionnaire items, while Chapter 13details how the ICCS results were reported and gives an account of the conventions adoptedfor the construction of tables.The ICCS technical report also contains a set of appendices. These list the organizations andindividuals involved in ICCS, describe the characteristics of the national samples, providedescriptions of the cognitive test items (including allocations of those items to proficiencylevels), and include tables featuring the coding information for the items in the questionnairesand the test.overview19