ABSTRACT
Statistical evidence in human populations can be divided into two types, namely observational statistical evidence, generally obtained by epidemiological studies, and interventional statistical evidence, generally obtained by clinical trials. Ancel Keys, who made a most important contribution to the study of coronary heart disease (CHD), was also a rather fascinating character. His focus on fat in the diet was suggested by some of his reading. The seven countries study is an example of what epidemiologists call a "cohort study" or "prospective study". The Cretan cohort is indeed something of an anomaly in the seven countries study. Despite having both an intake of saturated fat and blood cholesterol level much higher than the Japanese cohorts, the Cretan cohort had a lower incidence of coronary heart disease than either Japanese cohort. Its incidence of CHD was also much lower than that of the Italian cohorts from Crevalcore and Montegiorgio, who had comparable intakes of saturated fat and comparable blood cholesterol levels.
