Core C (Biostatistics & Data Management) provides expert support in the biostatistical aspects of the design, conduct and statistical analysis of research projects generated under the U54 and in the design and operation of database management systems. Core members will 1) work with investigators to select valid observational study designs, 2) design effective database management systems for storing and exporting relevant data, 3) interface closely with the Shared Resources Core, in the design of data collection tools and quality assurance methods, 4) conduct efficient and robust data analyses, create graphs and tables, assist investigators with the preparation of presentations and manuscripts, and consult on the design of subsequent research, and 5) serve as a statistical mentor in the Mentoring/Career Development Core. Core statisticians have extensive experience supporting HIV/AIDS and cancer research of all kinds and have existing collaborations with the Project leaders at their respective institutions. The Core's database programmer has comprehensive experience in developing databases, data queries/quality assurance procedures and data extraction programming to generate statistical analysis-ready files. We are thus highly qualified to provide biostatistics and data management support of the highest quality to the U54 research projects.