In addition to the following questions about TIMSS, more FAQs about international assessments are available at: http://nces.ed.gov/surveys/international/faqs.asp.
Yes. The composition of participating countries in TIMSS has changed somewhat from 1995 to 2007, as some countries have dropped out and others have joined.
In 2007, more than 56 separate countries participated in TIMSS. TIMSS also allows subnational entities to participate as benchmarking partners in the assessment. The subnational entities that participated in TIMSS 2007 were as follows: the Basque country in Spain, four Canadian provinces (Alberta, British Columbia, Ontario, and Quebec), Dubai, and two states in the United States (Massachusetts and Minnesota). In the case of the Canadian provinces, the Basque country, and Dubai, the larger nation in which they are located chose not to participate. In the case of the states of Massachusetts and Minnesota, students in these states were eligible for participation in the U.S. national sample as well as in the separate samples that these states drew for the study.