Trends in International Mathematics and Science Study (TIMSS 2027)
Main Study
Sampling, Recruitment, and Data Collection
OMB #1850-0695 v.21
Supporting Statement Part B
Submitted by
National Center for Education Statistics
Institute of Education Sciences
U.S. Department of Education
October 2025
B. Collection of Information Employing Statistical Information 1
B.3 Maximizing Response Rates 3
B.4 Purpose of the Main Study and Data Uses 5
There are four target populations for the TIMSS 2027 main study: two school populations and two student populations. The two school target populations include schools offering fourth-grade instruction and those offering eighth-grade instruction in the winter/spring of 2027 in the 50 states and the District of Columbia. These schools include:
Public schools, including charter and magnet schools;
Private schools; and
Bureau of Indian Education schools.
We plan to exclude the following schools from our main study samples:
Special education schools,
Virtual schools,
Domestic and international Department of Defense schools, and
Schools that include temporary housing like correctional facilities and hospitals.
There are two student target populations for the main study of TIMSS 2027: fourth- and eighth-grade students enrolled in winter/spring of 2027 in the United States (50 states and the District of Columbia) in a school in one of the two school target populations.
The school sample design for the main study uses probability sampling to select a sample of schools for grade 4 and a sample of schools for grade 8. The school samples will represent all schools, with the requisite grades, in the entire United States. The main study for TIMSS will take place in the spring of 2027.
The sample size for the TIMSS main study will be 180 schools at each of grades 4 and 8. The sampling frames of grade 4 and 8 schools will be obtained from NCES’ 2023-2024 Common Core of Data (CCD) and 2021-2022 Private School Universe Survey (PSS) files, restricted to schools having grade 4 or 8, respectively, and limited to schools in the 50 United States and the District of Columbia.
The school samples will be explicitly and implicitly stratified according to school characteristics. Explicit strata will be created by cross-classifying school type (public/private), Census region (Northeast, Midwest, South, and West), and poverty status (High/Low, as measured by the percentage of students in the school receiving free or reduced-price lunch in the National School Lunch Program (NSLP)). This will ensure an appropriate representation of each type of school in the selected sample of schools. Within each explicit stratum, schools will be hierarchically sorted by locale (city, suburb, town, rural), percent non-white (less than 15 percent, greater than or equal to 15 percent), State, and enrollment1 in the respective grade. Hierarchical sorting will result in samples within explicit strata being distributed approximately proportionately across the groups defined by the implicit stratification variables.
Schools will be selected with probability proportional to enrollment in the appropriate grade (4 or 8) using systematic probability proportional to size sampling. Because the number of classes in a given grade at a school is approximately proportional to the number of students enrolled in that grade, and because two classrooms will be sampled from participating schools, the use of a probability proportional to enrollment sample design ensures that all students have an approximately equal chance of selection.
Student sampling will be accomplished by selecting two classes per school. Participating schools will be asked to provide a list of students and classes. Students will be selected for participation by drawing a random sample of two classes in each school using software provided by the international TIMSS study coordinator. At grade 4, students will be selected by drawing a sample of two intact homeroom classrooms. At grade 8, students will be selected by drawing a sample of two intact mathematics classrooms (in which grade 8 students are enrolled) in each sampled school. Smaller classes may be combined to form ‘pseudoclasses’ for sampling. All selected students will be asked to participate in a combined TIMSS mathematics and science assessment. Only students in intact classrooms will be assessed at each grade. We estimate that on average 27 students will be selected from each school, and up to 10 percent of those students will be ineligible or excluded2 for the main study, yielding approximately 4,000 fourth grade and 4,000 eighth grade students.
TIMSS samples are typically designed to minimize overlap with NAEP data collections happening in the same time frame. There are no NAEP data collections currently scheduled for 2027. If NAEP or other NCES data collections are determined to be scheduled in a similar time frame, the TIMSS samples, which we expect will be drawn first, may be provided for NAEP or other NCES data collection to consider when selecting its sample.
Class and student lists will be gathered from participating schools electronically using a secure electronic filing process (as explained in Part A). Electronic filing provides advantageous features such as efficiency and data quality checks. Schools will access the electronic filing system through a web site.
Nonresponse Bias Analysis, Weighting, and Sampling Errors
We will conduct a nonresponse bias analysis pursuant to NCES statistical standards in order to determine where and how respondents and nonrespondents differ on available characteristics. Sampling errors, that account for unequal weighting, stratification, and probability sampling will be calculated for a selection of key estimates.
Gaining cooperation from school districts and schools is paramount to the success of TIMSS 2027, and also the most significant challenge of the study. Given that classrooms are selected, student participation is not as great of a challenge. Historically, weighted student participation rates in TIMSS have never fallen below 90 percent (see table 1). That said, it is important to U.S. TIMSS that students are engaged and try to do their best on the assessment.
Table 1. Historical TIMSS school and student participation rates
Year |
Grade |
School Participation Rate |
Overall Student Participation Rate |
|
Before Replacement |
After Replacement |
|||
2023 |
4 |
63 |
82 |
93 |
8 |
55 |
72 |
90 |
|
2019 |
4 |
76 |
88 |
96 |
8 |
72 |
85 |
94 |
|
2015 |
4 |
79 |
85 |
96 |
8 |
78 |
84 |
94 |
|
2011 |
4 |
79 |
84 |
95 |
8 |
87 |
87 |
94 |
|
2007 |
4 |
70 |
89 |
95 |
8 |
68 |
83 |
93 |
|
2003 |
4 |
70 |
82 |
95 |
8 |
71 |
78 |
94 |
|
1999 |
8 |
83 |
90 |
94 |
1995 |
4 |
86 |
NA |
|
Our approach to maximizing school recruitment is to:
Begin recruitment activities as early as possible;
Engage stakeholders at all levels throughout each cycle of TIMSS;
Obtain endorsements about the value of TIMSS from relevant national organizations, state and regional agencies. Ask these organizations to post about TIMSS on their social media or in newsletters and/or conduct direct recruitment activities;
Engage with the broad school community (i.e., not sampled schools) through involvement at small-scale school leader conferences and events, to provide an opportunity to test-drive our anticipated recruitment messages, build relationships with influential school-level leaders and highlight anticipated benefits of participation to build hope and excitement among schools that they may be selected into the study;
Inform Chief State Officers and state assessment directors about the sample of schools in their state and the schedule for upcoming NCES studies and assessments;
Provide a framework alignment guide for state assessment and accountability offices, which provides information on how to compare and contrast the TIMSS framework with individual state frameworks;
Partner with NAEP State Coordinators to recruit districts and schools, providing key state agency involvement in recruitment;
Send letters and informational materials to schools and districts;
Follow-up mailings with telephone calls and emails to explain the study and school involvement, including placing the TIMSS assessment date on school calendars. Provide flexibility in scheduling dates;
Gather and share information about how TIMSS data have been used to improve education in the past to help districts and schools understand the importance of TIMSS and how the data are used;
Maintain continued contact until schools have built a relationship with the recruiter and fully understand TIMSS;
Use monetary school incentives of at least $200 and up to $800 for select schools (see description in Part A.9);
Provide study updates for all levels on key study milestones and releases;
Make in-person visits to some districts and schools, as necessary;
Stress the low burden involved with TIMSS participation;
Emphasize confidentiality procedures.
Our approach to maximizing student recruitment is to:
Encourage schools to use implied permission forms or notification letters. Written permission will be collected if required by the school district or school;
Send parental permission forms home to parents 4-6 weeks ahead of the TIMSS sessions to allow ample time for parents to grant permission;
Offer participating students a small token of appreciation valued at approximately $4, for example ear buds, a digital watch, or a pair of sunglasses;
Provide students with a certificate with their name thanking them for participating and representing the United States in TIMSS;
If permitted by the school, this certificate will also serve as a certificate of service (4th and 8th grades) and/or community service hours (8th grade), as permitted by the school;
Encourage teachers to encourage student participation;
Ask schools to hang colorful, engaging posters in the school announcing participation;
When feasible, have the test administrator (TA) speak to student prior to the scheduled session day to encourage participation.
Our approach to maximizing teacher recruitment is to:
Send letters and materials reinforcing the importance of participation to teachers;
Follow up with prompting phone calls from RTI’s recruitment experts, who have already established relationships with the school during the school recruitment phase;
Request cell phone numbers for teachers and, if permitted, send text message reminders about the study;
Offer a $25 incentive for participation;
Have the TA speak to teachers in person on the day of the student session, or, if teachers are not available, have TA leave personalized postcard reminders in teacher mailboxes.
The goals of the TIMSS main study are to (1) provide trend information about student achievement in mathematics and science to inform education policy discussions; (2) provide comparative indicators on student performance and school practices across countries in order to benchmark U.S. student performance.
Data compiled and collected from TIMSS 2027 will allow for evidence-based decisions to be made for educational improvement. These high-quality, internationally comparative trend data are key to informing education policy discussions.
Overall direction for TIMSS is provided by Enis Dogan, National Research Coordinator, and Gina Broxterman, Contracting Officer's Representative, National Center for Education Statistics (NCES), U.S. Department of Education, in consultation with a number of NCES statistical staff.
The following persons are responsible for the statistical design of TIMSS:
Bethany Fishbein, TIMSS International Study Center, Boston College (617-552-1600); and
Peter Siegel, RTI International (919-541-6348).
RTI International is the contractor responsible for sampling, data collection, and data analysis:
Debbie Herget, Project Director, RTI International (919-485-7793);
McCaila Ingold-Smith, Associate Project Director, RTI International (919-990-8684); and
David Wilson, Senior Statistician, RTI International (919-541-6990).
Analysis and reporting will be performed by:
National Center for Education Statistics, U.S. Department of Education;
TIMSS International Study Center, Boston College; and
RTI International.
1 Enrollment less than 5 will be set to 5 for purposes of implicit stratification and sampling.
2 Students are considered ineligible if they are enrolled in the classroom but not in the target grade (grade 4 or grade 8) or if a student transferred from the school or class between the time that the student roster was prepared and the scheduled session at the school. Students are excluded if they meet the internationally defined criteria as having a functional disability, an intellectual disability, or if they are a non-native language speaker and unable to read or speak the language of the assessment. Students with functional or intellectual disabilities or have at least one year of English instruction or are able to overcome the language barrier would be included in the testing.
| File Type | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| Author | Millar, Kimrey |
| File Modified | 0000-00-00 |
| File Created | 2026-02-05 |