Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary physical model, and several graphics. Two examples show how the method is applied.
Osvaldo Marrero (Osvaldo.Marrero@villanova.edu) earned degrees from the University of Miami and from Yale, where he was also a postdoctoral research fellow. Subsequently, he completed courses at the University of Minnesota and at the Université de Montréal. He has worked in industry and academia, including affiliations with mathematical and medical groups at several universities. He has been a researcher in several units of Yale University’s medical school and served as an adjunct professor of pediatrics at the University of Pennsylvania. For many years, he has been a professor at Villanova. He has published papers in epidemiology, mathematics, medicine, and statistics. He’s known for mathematical work on combinatorial designs and related structures, and for statistical work on seasonal variation in epidemiological data. He has presented at professional meetings worldwide and delivered invited lectures at universities in the Americas and in Europe. When not working, he pursues other passions, too numerous to mention.