This textbook, Advising on research methods: A consultant’scompanion, has been written for those who give advice on researchmethods in the social and behavioral sciences, including medicine andepidemiology. It aims to assist researchers in the field toproduce better – more accurate, valid, and reliable – results.Herman J. Ader has been a statistical consultant for many years at VU University in Amsterdam first at the Psychology department, later at theVU Medical center. With Don Mellenbergh, he has given numerous courses on Methodological advising using the present book as material.Gideon J. Mellenbergh is emeritus professor of Psychological Methods at the Department of Psychology, University of Amsterdam. He has a long-standing experience in methodological consultancy in different fields, suchas clinical and health psychology, industrial and organizational psychology, educational research, social dentistry, and psychiatry.David J. Hand is Professor of Statistics at Imperial College, London, UK. He has wide-ranging consultancy experience to organizations ranging from banks, through pharmaceutical companies, to governments. He has published fifteen books, and is the founding editor and continuing editor-in-chief of the journal of Statistics and Computing.