is a Research Professor in the Survey Methodology Program, located within the Survey Research Center of the Institute for Social Research on the University of Michigan – Ann Arbor campus. He earned his PhD in 2011 from the Michigan Program in Survey and Data Science, and he also has an MA in Applied Statistics and a BS in Statistics from the University of Michigan – Ann Arbor Department of Statistics. He is presently the PI of the NIH-funded American Family Health Study (AFHS) and a co-I on the Health and Retirement Study (HRS). His current research interests include total survey error, selection bias in surveys, interviewer effects, responsive and adaptive survey design, survey paradata, the analysis of complex sample survey data, and the analysis of clustered and longitudinal data. The author of more than 200 peer-reviewed publications in survey methodology, applied statistics, and public health, he is the lead author of the book Linear Mixed Models: A Practical Guide Using Statistical Software (Third Edition, with Kathy Welch and Andrzej Galecki), and a co-author of the book Applied Survey Data Analysis (with Steven Heeringa and Pat Berglund). He was elected as a Fellow of the American Statistical Association in 2022.
is a Research Associate Professor in the Survey Methodology Program, the Survey Research Center, the Institute for Social Research at the University of Michigan. She holds a PhD from the Joint Program in Survey Methodology at the University of Maryland. She is the PI of two NIA-funded studies: Project Positive Attitudes Towards Health and Health and Well-being of Koreans. She also leads the sample aspect of the Health and Retirement Study.
Her research interests include sampling and measurement issues in data collection with racial, ethnic and linguistic minorities as well as hard-to-reach populations and cross-cultural survey methodology.
is a Research Associate Professor at the Survey Research Center (SRC) of the Institute for Social Research (ISR) on the University of Michigan, Ann Arbor campus, where she also serves as Associate Director of the Panel Study of Income Dynamics (PSID) and Director of the External Innovative Networks Core at the Michigan Center on the Demography of Aging (MiCDA). Her research focuses on the role of family caregiving and long-term care for the health and wellbeing of older adults, particularly those with dementia. In her work, She collects primary data and also analyzes secondary data from a variety of longitudinal survey datasets of aging. Friedman is currently one of the PIs of the PSID and PI of an NIA-R01 for which she is collecting new data on the social networks of family caregivers to identify typologies of caregiver support networks, how they changed during the COVID-19 pandemic, and the implications for caregiver and care recipient health and wellbeing outcomes. She has several other ongoing projects on long-term care availability and use, and the impact of long-term care policies on health disparities.