Tarun Kumar Roy is former Director of the International Institute for Population Sciences (IIPS) in Mumbai. He served as a faculty member at IIPS for more than three decades and taught courses on sampling design and the evaluation of family welfare programs to graduate students. He was actively engaged in conducting several large-scale surveys, and was engaged in the National Family Health Survey (also known as the India Demographic and Health Survey). He serves as an expert on the Sampling Review Committee for the Global Adult Tobacco Survey (GATS), being conducted by the National Foundation for the Centers for Disease Control and Prevention in Atlanta, USA. Rajib Acharya is a statistician and demographer with more than fifteen years' experience in academic research, and planning, designing, managing and monitoring large studies. He worked as a Research Advisor at Johns Hopkins University from 2002 to 2004. He has expertise in the design of large sample surveys, sample size determination, processing and managing large-scale cross-sectional and longitudinal data sets and the analysis of survey data on population, health and nutrition. He has published a number of articles in national and international journals. Arun Roy is Chief Executive of Economic Information Technology, a socio-economic research organization in Kolkata. He received an MSc in Statistics from Patna University, an MA in Economics from Delhi University, and a PhD in Sociology from Kalyani University. He has worked as an economist at the National Council of Applied Economic Research, New Delhi, and has served as a Monitoring and Evaluation Consultant to several organizations, including the World Bank in Odisha, the Institutional Council on Management of Population Programs in Malaysia, and German Agro Action in Bonn.