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Ralph Folsom, PhD, chief sientist for Statistical, Survey, and Computing Sciences at RTI, is an expert in the design and analysis of complex probability samples. Working on the nation’s largest household survey (the National Survey on Drug Use and Health or NSDUH), Dr. Folsom initiated innovative weight adjustment methods based on his logistic response propensity and exponential poststratification models. This pioneering work led to the sophisticated GEM weight adjustment methods currently employed for NSDUH. 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 recently led RTI’s innovative work in small area estimation research. In addition to his innovative work on many complex survey efforts, Dr. Folsom has made significant contributions to the development of RTI’s computer software for survey data analysis, SUDAAN. | 