To the Editor:—
In his article, "Diet in Coronary Atherosclerosis," in The Journal, June 25, page 884, Dr. Morrison reports that 100 patients who had survived the first four to six weeks after myocardial infarction were alternately assigned to a normal diet group and a low-fat, low-cholesterol diet group. Mortality for each group was reported at 3, 5, and 12 years after infarction. Survival figures for the low-fat, low-cholesterol group were superior at all three intervals, but the author states, "Statistical evaluation of the 100 patients reported in this study is impractical because of the smallness of the sample."A skeptic may question whether unconscious bias might be present as a result of selection of cases, the chance distribution of irrelevant but prognostically important characteristics, or important differences other than diet in the subsequent management. It appears unlikely that significant bias is present. Assuming no bias, there is a relatively