TIMSS 2015 Data
All statistics were computed using sampling weights.
All achievement data were presented as five plausible values. All required statistics were calculated separately for each of the plausible values and the resulting statistics averaged to get the final result.
Standard errors for significance testing of achievement results were computed using the
- Jackknife repeated replication method (JK2 variant) to estimate sampling variance, and
- Differences between the five plausible values to estimate measurement variance.
General note: TIMSS 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.
TIMSS data and the International Database are freely available.
For secondary analyses, data can be analyzed with IEA IDB Analyzer and the International Data Explorer. These tools take into account the characteristics of the sampling and assessment design and implement the jackknife replication method with the appropriate plausible values.
- Background questionnaires (school, teacher, student, and home/early learning survey)
- Curriculum questionnaires
- Achievement responses to assessment items (see below under item release policy)
- Scoring reliability
- Test-curriculum matching analysis (TCMA) data
Responses to all items used in the assessment are included in the database; after each cycle, some of the assessment items are made available for restricted use by the public. The remaining items are kept secure, thus ensuring the possibility of measuring trends over time. Access to the restricted-use items is subject to approval by IEA Amsterdam. The response data for all items used in the assessment, however, are publicly and freely available in the data files. The item release policy is described in the Item Release Plan.