Imputation

Biography
Ralph Folsom, PhD and Chief Scientist for Statistical, Survey, and Computing Sciences at RTI, is an expert in the design and analysis of complex probability samples. Working on the National Survey on Drug Use and Health (NSDUH), Dr. Folsom initiated innovative weight adjustment methods based on his logistic response propensity and exponential poststratification models. Dr. Folsom also introduced model-based imputations for missing frequency of use and income data items, and he has been an influential collaborator in the development of NSDUH’s current Predictive Mean Neighborhoods (PMN) imputation methodology. Dr. Folsom has made significant contributions to the development of RTI’s computer software for survey data analysis, SUDAAN. These contributions include sample design-based modes of estimation and inference for linear and logistic regression coefficients. Read More…

Biography
Vincent G. Iannacchione, a senior research statistician, has been with RTI for over 22 years. He directs statistical operations for national surveys on health care, drug abuse, education, and military studies. He designs and selects samples, including multistage area and list sampling, network sampling, and double sampling for nonresponse. He directs the computation of sampling weights and the imputation of missing data, and he supervises data analysis. Read More…

Biography
Phillip S. Kott, PhD, is a senior research statistician and an expert in survey sampling theory and practice, including calibration weighting, multiphase sampling, the analysis of survey data, and variance estimation. Dr. Kott is a fellow of the American Statistical Association (ASA), a member of the International Statistical Institute, and a fellow of the Royal Statistical Society. He received a Presidential Rank Award in 2007 and an ASA Section of Statistics and the Environment Distinguished Achievement Medal in 1997. He is active as a journal associate editor, and served as the president of the Washington Statistical Society and the chair of ASA's Council of Chapters. He has taught survey sampling at George Mason University and the Joint Program in Survey Methodology. Prior to joining RTI in January 2009, Dr. Kott was the chief research statistician at the National Agricultural Statistical Service of the United States Department of Agriculture. Read More…

Biography
Roy Whitmore, PhD, is a senior statistician who joined RTI in 1980. He is expert in design and analysis of complex sample surveys. His primary areas of application have been human exposure assessment surveys and postsecondary education studies. He recently was principal investigator for an EPA STAR grant that developed a data collection platform for human exposure-related behaviors, including time/activity/location/exertion-level data, dietary data, and data on use of consumer products. He was sampling task leader for such high-visibility EPA studies as the EPA Region 5 field test of the National Human Exposure Assessment Survey. He has served as task leader for sampling, weighting, imputation, and reporting for several postsecondary education surveys for the National Center for Education Statistics. He has published in the Journal of Exposure Science and Environmental Epidemiology, Environmental Health Perspectives, Environmental Science and Technology, Atmospheric Environment, Journal of Official Statistics, and Journal of the American Statistical Association. Read More…