Studies encompassing childhood and adolescence face the particular challenge of the transitions from pre-school to primary school and from childhood to adolescence; accordingly, the instruments used need to be adapted to different developmental stages while maintaining their comparability across the age range. In young children, questionnaires have to be completed by proxies, usually their parents, while older children, particularly adolescents, can provide a major part of the requested information themselves.

This book presents suitable designs, methods and instruments for data collection in studies of children and adolescents. Each chapter explains the development and background of the instruments applied in the surveys and summarises the current state of knowledge. All chapters were written by key experts in their respective research fields. We are grateful for their valuable contributions and their enthusiastic support in producing this book, which also presents survey experiences in which practice does not always follow theory. Participants responses can on occasion be unexpected and unpredictable, but meeting these challenges can also enrich epidemiological surveys and yield methodological refinements. We sincerely hope that the book and the online material will be of considerable value to other research teams.

Karin Bammann

Department of Epidemiology of Demographic Change, Institute for Public Health and Nursing Research (IPP), University of Bremen, Germany

Karin Bammann has been a Senior Researcher at the Department of Human and Health Sciences of the University of Bremen since 2011. Her teaching focuses on empirical and epidemiological methods, project management, and lifestyle related diseases. As head of the Department of Epidemiology of Demographic Change at the Institute for Public Health and Nursing Research (IPP), she has extensive experience in conducting and managing epidemiological studies, and in primary data collection. Her research currently concentrates on health and disease during the life course, and on physiological, social and contextual determinants thereof. A second focus is on empirical research methodologies, especially on the application of mixed methods and participatory research methods in Public Health and epidemiology. She was an international scientific manager and responsible for instruments, standardisation and quality management in the largest pan-European childrens cohort, including more than 18,000 children, the IDEFICS cohort. She has published more than 80 international peer-reviewed papers, 11 book chapters, and three books.

Lauren Lissner

Lauren Lissner is a Professor of Epidemiology at the Section for Epidemiology and Social Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden. She holds a Master of Public Health degree from the University of California at Los Angeles and a PhD in Human Nutrition from Cornell University. Prof. Lissner has been living in Sweden since 1989 and is former president of the Swedish Association for the Study of Obesity. Since 2006, she has represented Sweden on the Steering Committee of IDEFICS and I.Family Studies. She has published around 350 peer-reviewed articles, mainly in the areas of obesity andnutrition epidemiology.

Iris Pigeot

Department of Biometry and Data Management, Leibniz Institute for Prevention Research and Epidemiology BIPS, Bremen; University of Bremen, Institute of Statistics, Bremen, Germany

Iris Pigeot has been a Professor of Statistics with a focus on biometry and methods in epidemiology at the Department of Mathematics and Computer Science, University of Bremen since 2001. She is director of the Leibniz Institute for Prevention Research and Epidemiology BIPS and head of the Department of Biometry and Data Management. Her research activities focus on bioequivalence studies, graphical models, and genetic epidemiology. In recent years she has broadened the scope of her research to include the use of secondary data in the research of pharmaceutical drug safety as well as primary prevention and its evaluation, especially for childhood obesity. She was deputy coordinator of the largest pan-European childrens cohort, including more than 18,000 children, the IDEFICS/I.Family cohort. She has received several teaching awards: the Medal for Excellent Teaching at the University of Dortmund in 1994, the Award for Quality Teaching at the University of Munich in 1996, and the Berninghausen Award for Excellent Teaching and its Innovation at the University of Bremen in 2008. In 2010 the IBS-DR awarded her the Susanne-Dahms medal for special accomplishments in the field of biometry. She has authored or co-authored four books, the most recent being a German textbook Epidemiological Methods (Springer 2012), and has edited or co-edited three books, most recently the Handbook of Epidemiology (Springer 2014).

Wolfgang Ahrens

Department of Epidemiological Methods and Etiological Research, Leibniz Institute for Prevention Research and Epidemiology BIPS, Bremen; University of Bremen, Institute of Statistics, Bremen, Germany

Wolfgang Ahrens has been a Professor of Epidemiological Methods at the Department of Mathematics and Computer Science, University of Bremen since 2003. He is scientific deputy director of the Leibniz Institute for Prevention Research and Epidemiology BIPS and head of the Department of Epidemiological Methods and Etiological Research. Wolfgang Ahrens is an epidemiologist with considerable experience in leading population-based (inter)national multi-centre studies involving primary data collection. His research focuses on exposure assessment and the aetiology and primary prevention of non-communicable diseases, especially cancer, nutrition- and lifestyle-related disorders. He coordinated the largest pan-European childrens cohort, including more than 18,000 children, the IDEFICS/I.Family cohort. He has published more than 220 international peer-reviewed papers and 16 book chapters. He has authored / co-authored three books, the most recent being a German textbook Epidemiological Methods, and has edited or co-editedsix books, most recently the second edition of the Handbook of Epidemiology.