Trends in International Mathematics and Science Study (TIMSS)

3. KEY CONCEPTS

Key terms related to TIMSS are described below.

International Desired Population. The International Desired Population (also referred to as the International Target Population) is the target population which, in general, is defined for TIMSS at the lower grade as all students in their fourth year of formal schooling and, at the upper grade, all students in their eighth year of formal schooling. See the Target Population section below for more specifics.

National Desired Population. The stated objective in TIMSS is that the National Desired Population (also referred to as the National Target Population) within each country or education system be as close as possible to the International Desired Population . Using the International Desired Population as a basis, participating countries and other education systems must operationally define their populations for sampling purposes. Some countries and other education systems want to restrict coverage at the country or other education system level, by excluding remote regions or a segment of their country's education system, for example. Thus, the National Desired Population sometimes differs from the International Desired Population.

National Research Coordinators (NRCs). This is an official from each participating country or other education system appointed to implement national data collection and processing in accordance with international standards. In addition to selecting the sample of students, NRCs are responsible for working with school coordinators, translating the test instruments, assembling and printing the test booklets, and packing and shipping the necessary materials to the sampled schools. They are also responsible for arranging the return of the testing materials from the school to the national center, preparing for and implementing the constructed-response item scoring, entering the results into data files, conducting on-site quality assurance observations for a 10 percent sample of schools, and preparing a report on survey activities.