The Advanced Statistical Methods Core (ASC) is designed to remedy current deficiencies in the availability of advanced statistical services to BNCD Center researchers. The Core, consisting of a Statistician and Statistical Assistant, will: (1) Assist Center investigators by planning and conducting tdvanced statistical analyses using cutting-edge methods including mixed modeling, structural equation modeling, time-series analysis and other techniques for the analysis of multivariate, longitudinal data. (2) Assist Center investigators with grant proposal preparation and final report preparation including write-up of methods, procedures, and results sections. (3) Train Center investigators in applications of advanced statistical techniques. Services provided by the Advanced Statistical Methods Core will expand, rather than duplicate, educational training provided by the Quantitative Psychology Program, basic statistical services provided by the Research Design and Analysis Unit, a component of the Life Span Institute, and basic training provided by the Academic Computing Center. These existing resources cannot meet current demand for advanced statistical methods and are particularly limited with regards to methods addressing the analysis of change over time, groups, and individuals. The Advanced Statistical Methods Core will provide Center investigators with the ability to use new methods, including mixed modeling (growth curve modeling), structural equation modeling and dynamic structural modeling, as well as new techniques for time-series analysis. All of these techniques have in common the focus on the detection of individual and group differences in patterns of growth and change--modeling intra-individual differences in intmindividual growth. They raise significant questions regarding the treatment of incomplete data (and attrition), factorial invariance, and intraindividual variability - and the application of new methods to address these concerns.