Trude Nilsen is a research professor at the Department of Teacher Education and School Research at the University of Oslo, Norway. She holds a PhD in science education and her thesis was awarded the IEA Bruce H. Choppin Memorial Award.  She is the leader of the research group Large-scale Educational Assessment (LEA) at her department, and a leader of the large project Teachers’ Effect on Student Outcome (TESO). TESO is funded by the Norwegian Research Council and is a longitudinal extension of TIMSS. In addition, her work comprises analyzing data from the main ILSAs and supervising PhD students. Of all the ILSAs, TIMSS has been the main focus since 2010, and she is, and has been, an international external expert in the Questionnaire Item Review Committee (QIRC) for TIMSS 2019 and 2023. She also has worked as an external expert for the OECD in the Questionnaire Expert Group (QEG) for TALIS 2018 and the TALIS Starting Strong 2018. She has published a large numberof articles in international and national journals as well as books, such as the award winning and widely disseminated Springer book Teacher Quality, Instructional Quality and Student Outcome. Relationships Across Countries, Cohorts and Time. These publications primarily pertain to the areas of educational and teacher effectiveness. Using ILSA data she focuses on school climate and teacher instructional quality as well as educational equality and applied methodology including causal inferences.Agnes Stancel-Piątak is a Senior Researcher at the International Association for the Evaluation of the Educational Achievement (IEA Hamburg, Germany). She holds a PhD in education. Her scientific work focuses primarily on social justice and educational effectiveness on the one hand, and on study and test development and implementation on the other. Moreover, in the context of large-scale assessments her interest is on overarching concepts describing the schoolsystem. Applied to ILSAs, these concepts contribute to enhance the theoretical framing and to strengthen the alignment between different ILSAs. Agnes Stancel-Piątak acts as an expert for the IEA, the Organisation for Economic Co-operation and Development (OECD), and other international scientific organizations and national governmental entities in test construction and complex methods of data analysis. She was and is a member of the Questionnaire Expert Group (QEG) for TALIS 2018, TALIS Starting Strong Survey 2018, and the upcoming TALIS 2024. She leads the scaling team within the IEA Hamburg which is responsible for the psychometric foundation of these studies.Jan-Eric Gustafsson is professor emeritus of education at the University of Gothenburg. His research has primarily focused on basic and applied topics within the field of educational psychology. Three main categories of questions have been in focus: individual prerequisites for education; effects of resources for andorganization of education; and educational outcomes at individual and system levels. The research on individual prerequisites for education has in particular focused on the structure of cognitive abilities that has resulted in a hierarchical model which integrates several previous models of individual differences in cognitive abilities.  The research on educational determinants and outcomes has primarily been based on data collected within the international large-scale assessments, and particularly so in the studies conducted by IEA. Gustafsson has also been involved in development of quantitative methodology, focusing on issues of measurement with the Rasch model and on techniques for statistical analysis with latent variable models. He was for almost two decades a member of the IEA Technical Executive Group, which advises on design, analysis and reporting of the IEA studies. To an increasing extent he has also become involved in national educational policy issues and he chaireda governmental School Commission, aiming for improvements of the quality and equity of the Swedish school system. In 1993 he was elected member of the Royal Swedish Academy of Sciences and in 2020 he was elected Corresponding Fellow of the British Academy.

• About this Handbook.- Meta-perspectives on ILSAs. Theoretical metaperspectives on ILSAs.- Meta-perspectives on ILSAs. The role of theory in ILSAs.- Meta-perspectives on ILSAs. Characteristics of ILSAs.- Meta-perspectives on ILSAs. Accomplishments, limitations, and recommendations.- Methodology. Designing and implementing ILSAs.- Methodology. Methods of Analysis.- Methodology. Potential and methods of linking ILSA to national education policy and research.- Findings. Schools, principals, and institutions.- Findings. Classrooms, teachers, and curricula.- Findings. Students, competences, and dispositions.- Findings. Equity and diversity.- Concluding remarks.

Trude Nilsen is a research professor at the Department of Teacher Education and School Research at the University of Oslo, Norway. She holds a PhD in science education and her thesis was awarded the IEA Bruce H. Choppin Memorial Award.  She is the leader of the research group Large-scale Educational Assessment (LEA) at her department, and a leader of the large project Teachers’ Effect on Student Outcome (TESO). TESO is funded by the Norwegian Research Council and is a longitudinal extension of TIMSS. In addition, her work comprises analyzing data from the main ILSAs and supervising PhD students. Of all the ILSAs, TIMSS has been the main focus since 2010, and she is, and has been, an international external expert in the Questionnaire Item Review Committee (QIRC) for TIMSS 2019 and 2023. She also has worked as an external expert for the OECD in the Questionnaire Expert Group (QEG) for TALIS 2018 and the TALIS Starting Strong 2018. She has published a large numberof articles in international and national journals as well as books, such as the award winning and widely disseminated Springer book Teacher Quality, Instructional Quality and Student Outcome. Relationships Across Countries, Cohorts and Time. These publications primarily pertain to the areas of educational and teacher effectiveness. Using ILSA data she focuses on school climate and teacher instructional quality as well as educational equality and applied methodology including causal inferences.Agnes Stancel-Piątak is a Senior Researcher at the International Association for the Evaluation of the Educational Achievement (IEA Hamburg, Germany). She holds a PhD in education. Her scientific work focuses primarily on social justice and educational effectiveness on the one hand, and on study and test development and implementation on the other. Moreover, in the context of large-scale assessments her interest is on overarching concepts describing the schoolsystem. Applied to ILSAs, these concepts contribute to enhance the theoretical framing and to strengthen the alignment between different ILSAs. Agnes Stancel-Piątak acts as an expert for the IEA, the Organisation for Economic Co-operation and Development (OECD), and other international scientific organizations and national governmental entities in test construction and complex methods of data analysis. She was and is a member of the Questionnaire Expert Group (QEG) for TALIS 2018, TALIS Starting Strong Survey 2018, and the upcoming TALIS 2024. She leads the scaling team within the IEA Hamburg which is responsible for the psychometric foundation of these studies.Jan-Eric Gustafsson is professor emeritus of education at the University of Gothenburg. His research has primarily focused on basic and applied topics within the field of educational psychology. Three main categories of questions have been in focus: individual prerequisites for education; effects of resources for andorganization of education; and educational outcomes at individual and system levels. The research on individual prerequisites for education has in particular focused on the structure of cognitive abilities that has resulted in a hierarchical model which integrates several previous models of individual differences in cognitive abilities.  The research on educational determinants and outcomes has primarily been based on data collected within the international large-scale assessments, and particularly so in the studies conducted by IEA. Gustafsson has also been involved in development of quantitative methodology, focusing on issues of measurement with the Rasch model and on techniques for statistical analysis with latent variable models. He was for almost two decades a member of the IEA Technical Executive Group, which advises on design, analysis and reporting of the IEA studies. To an increasing extent he has also become involved in national educational policy issues and he chaireda governmental School Commission, aiming for improvements of the quality and equity of the Swedish school system. In 1993 he was elected member of the Royal Swedish Academy of Sciences and in 2020 he was elected Corresponding Fellow of the British Academy.

• About this Handbook.- Meta-perspectives on ILSAs. Theoretical metaperspectives on ILSAs.- Meta-perspectives on ILSAs. The role of theory in ILSAs.- Meta-perspectives on ILSAs. Characteristics of ILSAs.- Meta-perspectives on ILSAs. Accomplishments, limitations, and recommendations.- Methodology. Designing and implementing ILSAs.- Methodology. Methods of Analysis.- Methodology. Potential and methods of linking ILSA to national education policy and research.- Findings. Schools, principals, and institutions.- Findings. Classrooms, teachers, and curricula.- Findings. Students, competences, and dispositions.- Findings. Equity and diversity.- Concluding remarks.

Trude Nilsen is a research professor at the Department of Teacher Education and School Research at the University of Oslo, Norway. She holds a PhD in science education and her thesis was awarded the IEA Bruce H. Choppin Memorial Award.  She is the leader of the research group Large-scale Educational Assessment (LEA) at her department, and a leader of the large project Teachers’ Effect on Student Outcome (TESO). TESO is funded by the Norwegian Research Council and is a longitudinal extension of TIMSS. In addition, her work comprises analyzing data from the main ILSAs and supervising PhD students. Of all the ILSAs, TIMSS has been the main focus since 2010, and she is, and has been, an international external expert in the Questionnaire Item Review Committee (QIRC) for TIMSS 2019 and 2023. She also has worked as an external expert for the OECD in the Questionnaire Expert Group (QEG) for TALIS 2018 and the TALIS Starting Strong 2018. She has published a large numberof articles in international and national journals as well as books, such as the award winning and widely disseminated Springer book Teacher Quality, Instructional Quality and Student Outcome. Relationships Across Countries, Cohorts and Time. These publications primarily pertain to the areas of educational and teacher effectiveness. Using ILSA data she focuses on school climate and teacher instructional quality as well as educational equality and applied methodology including causal inferences.Agnes Stancel-Piątak is a Senior Researcher at the International Association for the Evaluation of the Educational Achievement (IEA Hamburg, Germany). She holds a PhD in education. Her scientific work focuses primarily on social justice and educational effectiveness on the one hand, and on study and test development and implementation on the other. Moreover, in the context of large-scale assessments her interest is on overarching concepts describing the schoolsystem. Applied to ILSAs, these concepts contribute to enhance the theoretical framing and to strengthen the alignment between different ILSAs. Agnes Stancel-Piątak acts as an expert for the IEA, the Organisation for Economic Co-operation and Development (OECD), and other international scientific organizations and national governmental entities in test construction and complex methods of data analysis. She was and is a member of the Questionnaire Expert Group (QEG) for TALIS 2018, TALIS Starting Strong Survey 2018, and the upcoming TALIS 2024. She leads the scaling team within the IEA Hamburg which is responsible for the psychometric foundation of these studies.Jan-Eric Gustafsson is professor emeritus of education at the University of Gothenburg. His research has primarily focused on basic and applied topics within the field of educational psychology. Three main categories of questions have been in focus: individual prerequisites for education; effects of resources for andorganization of education; and educational outcomes at individual and system levels. The research on individual prerequisites for education has in particular focused on the structure of cognitive abilities that has resulted in a hierarchical model which integrates several previous models of individual differences in cognitive abilities.  The research on educational determinants and outcomes has primarily been based on data collected within the international large-scale assessments, and particularly so in the studies conducted by IEA. Gustafsson has also been involved in development of quantitative methodology, focusing on issues of measurement with the Rasch model and on techniques for statistical analysis with latent variable models. He was for almost two decades a member of the IEA Technical Executive Group, which advises on design, analysis and reporting of the IEA studies. To an increasing extent he has also become involved in national educational policy issues and he chaireda governmental School Commission, aiming for improvements of the quality and equity of the Swedish school system. In 1993 he was elected member of the Royal Swedish Academy of Sciences and in 2020 he was elected Corresponding Fellow of the British Academy.

• About this Handbook.- Meta-perspectives on ILSAs. Theoretical metaperspectives on ILSAs.- Meta-perspectives on ILSAs. The role of theory in ILSAs.- Meta-perspectives on ILSAs. Characteristics of ILSAs.- Meta-perspectives on ILSAs. Accomplishments, limitations, and recommendations.- Methodology. Designing and implementing ILSAs.- Methodology. Methods of Analysis.- Methodology. Potential and methods of linking ILSA to national education policy and research.- Findings. Schools, principals, and institutions.- Findings. Classrooms, teachers, and curricula.- Findings. Students, competences, and dispositions.- Findings. Equity and diversity.- Concluding remarks.