however the survey method does provide information about issues especially perceptions that could not be obtained through other methods in addition the talis video study will provide important perspectives on the validity of selfreport data because it will collect both survey and video data because the database does not allow identification of classrooms it is not possible to link teachers with their class students student outcomes can therefore be associated only with the schoolaggregated indicator of teachers that review argued for better national and international information on teachers these were attracting developing and retaining effective teachers school policies and effectiveness and quality teachers and teaching