This thesis describes regression analysis and shows how it can be used in account auditing and in computer system performance analysis. The study first introduces regression analysis techniques and statistics. Then, the use of regression analysis in auditing to detect "out of line" accounts and to determine audit sample size is discussed. These applications led to the concept of using regression analysis to predict job completion times in a computer system. The feasibility of this application of regression analysis was tested by constructing a predictive model to estimate job completion times using a computer system simulator. The predictive model's performance for the various job streams simulated shows that job completion time prediction is a feasible application for regression analysis.