This competing training grant renewal application requests support for one postdoctoral trainee and two pre-doctoral trainees per year for five years. This proposed training in the Department of Biostatistics is designed for research training in the application of statistical theory and methods related to problems in the population field. A typical pre-doctoral trainee will be a college graduate with excellent undergraduate record, expertise in mathematics to at least the level of multivariable calculus and preferably some experience in the population field. Pre-doctoral trainees will complete a curriculum that includes courses in statistical theory and methods and in demographic techniques and modeling. Postdoctoral trainees undertake a training program for two years under the supervision of one or more program faculty members. A typical postdoctoral trainee will have a doctoral degree with strong quantitative skills and interest in population research. ? ? ?