We plan to continue our investigations regarding the efficiency of designs for clinical trails and epidemiologic studies. We shall expand our survey of cancer clinical trails to examine the relation of the design used to the quality of the study and the nature of the results obtained. We shall analyze a breast cancer case- control study to explore the practical application of the methodology we have developed for case-control studies with prevalent cases. We shall further explore this model to better understand the limitations of its stationarity assumptions, and its usefulness in analyzing matched data.