TIMSS 2015 Design
Methodology
- International large-scale sample-based assessment of student achievement and survey of the educational context
- Monitors trends in student achievement since 1995 by reporting results from successive cycles on a common achievement scale
- Predominantly quantitative, with qualitative information presented in descriptive country chapters in the TIMSS 2015 encyclopedia
Method(s)
- Overall approach to data collection
- Proctored assessment of student achievement
- Self-administered surveys for students, parents, teachers, and school principals
- Specification
- Cross-sectional
- Some trend reporting possible with previous cycles
Target population
- Grade 4: All students enrolled in the grade that represented four years of schooling, counting from the first year of ISCED Level 1, provided that the mean age at the time of testing was at least 9.5 years.
- Grade 8: All students enrolled in the grade that represented eight years of schooling, counting from the first year of ISCED Level 1, provided that the mean age at the time of testing was at least 13.5 years.
- In countries where Grade 4 or Grade 8 students were expected to find the TIMSS assessments too difficult, Grade 6 or Grade 9, respectively, were defined as the target populations.
Sample design
Stratified two-stage cluster sampling design
First stage: sampling schools
- Selection probability proportional to the size of the school (PPS)
- Optional: stratification of schools according to (demographic) variables of interest (e.g., school type or source of funding, level of urbanization, region of the country), either explicit or implicit
- Random-start fixed-interval systematic sampling
- Schools sampled at the same time for field trial and main data collection
- For each sampled school, two replacement schools were assigned where possible
Second stage (students): sampling classes
Within schools agreeing to participate:
- Systematic random sampling was used to select one or more classes from the sampled school in the target grade.
- Each class had an equal selection probability within the school.
- If a selected class was smaller than half of the average class size, a pseudo-class was created with other classes.
- All students within a selected class were asked to participate.
General notes
- Sampling of schools was conducted by Statistics Canada and the sampling team at IEA Hamburg.
- Sampling procedures within the center/school were carried out by the national study centers, using the Within-school Sampling Software for Windows (WinW3S) provided by IEA.
- All sampling activities were monitored and documented by Statistics Canada and IEA Hamburg staff.
Sample size
Intended per country and target grade
- Approx. 4,500 assessed students
- A minimum of 150 schools (in countries with fewer than 150 schools, all available schools were included)
- In each sampled school, selection of one class
- Required effective sample size: minimum of 400 students
Total achieved
- Grade 4: Approximately 312,000 students, 250,000 parents, 20,000 teachers, and 10,000 schools from 57 education systems (50 countries and 7 benchmarking entities) participated.
- Grade 8: Approximately 270,000 students, 31,000 teachers, and 8,000 schools from 46 education systems (39 countries and 7 benchmarking entities) participated.
Data collection techniques and instruments
Student assessments in mathematics and science
- Written format
- Two types of questions
- Multiple-choice (at least half of the total number of points)
- Constructed-response
- Achievement items
- A total of 28 item blocks per grade (14 with mathematics items, 14 with science)
- Items per block
- Grade 4: 10–14 items in each block
- Grade 8: 12–18 items in each block
- Items per block
- A total of 14 test booklets per grade – 4 blocks (2 mathematics, 2 science, in counterbalanced order) per booklet
- Items per assessment
- Grade 4: approx. 170 items in each of mathematics and science
- Grade 8: approx. 200 items in each of mathematics and science
- Items per assessment
- Linking mechanisms between booklets and between cycles
- New items in 2015: 12 blocks (6 mathematics and 6 science)
- The other 8 blocks (for each subject) are trend items (unreleased items) from TIMSS 2011 and 2007.
- A total of 28 item blocks per grade (14 with mathematics items, 14 with science)
- Matrix sampling of items (rotated test booklet design)
Background questionnaires
- Student questionnaire in print format modular design in Grade 4
- Teacher questionnaire to be completed by the mathematics and science teachers of assessed classes, print or online; modular design in Grade 4
- School questionnaire to be completed by the principal of each school sampled in print or online format
- Home questionnaire to be completed by students’ parents or guardians in print or online format
Curriculum questionnaires
- To be completed by NRCs in each participating entity
- Modular design
- Online format
Descriptive encyclopedia chapters
- One chapter for each participating entity
- Written by experts from ministries of education, research institutes, or institutions of higher education (in countries and benchmarking entities) based on an internationally agreed-upon outline
Languages
- Assessment instruments administered in 43 languages
- Instruments (assessments of achievement and student questionnaires) administered in two or more languages in 22 countries and five benchmarking entities
- The most common languages: English (21 countries), Arabic (10 countries)
Translation procedures
- International version of all assessment instruments developed in English by TIMSS & PIRLS International Study Center.
- Instruments then translated by participating countries into their languages of instruction.
- Translations verified by independent linguistic and assessment experts in order to ensure equivalence with the international version.
Quality control of operations
During data collection
- National research coordinator (NRC) in each participating country responsible for data collection
- Standardized survey operations procedures: step-by-step documentation of all operational activities provided with manuals
- Full-scale field test of all instruments and operational procedures (in each participating country and benchmarking entity)
- Provision of software tools for supporting activities (e.g., sampling and tracking classes and students, administering school and teacher questionnaires, documenting scoring reliability, creating and checking data files)
- Training of NRCs and their staff, school coordinators, test administrators, etc.
- School visits conducted by international quality control monitors (IQCMs) during test administration (15 schools per grade and country)
- National quality control program
- Survey activities questionnaire (SAQ) to be completed by NRCs
During data processing and cleaning
- Testing of all data cleaning programs with simulated data sets
- Material receipt database
- Standardized cleaning process
- National adaptation database
- Repetition of data cleaning and comparison of new data sets with preceding versions
- Identification of irregularities in data patterns and correction of data errors
Sources - Technical documentation
Other sources