ICCS 2009 Data
All statistics were computed using sampling weights.
Estimation of standard errors for significance testing were computed by means of:
- Replication methods (jackknife repeated replication, JRR) to estimate sampling variance
- Five plausible values for estimating measurement variance
- For doing secondary analyses, data can be analyzed with the IEA IDB Analyzer. This tool takes into account the characteristics of the sampling and assessment design, implements the corresponding replication method, and makes use of existing plausible values.
- General note: ICCS 2009 data are designed for group-level reporting; students’ scale scores in the database are not intended to report performance of individual students or very small groups.
Types of data files
- Background questionnaires (school, teacher, student)
- Achievement responses to assessment items
- Scoring reliability
- National context questionnaire
Item release policy
Responses to all items used in the assessment are included in the database. Some of the items are released to the public for informational purposes. The remaining items are kept secure, thus ensuring the possibility of re-using these in the next cycle of ICCS. While use of the actual released items is subject to approval by the IEA Secretariat, the response data to all items used in the assessment is publicly available in the data files.