Whether non–high-density lipoprotein cholesterol is equivalent to apolipoprotein B (apo B) for screening remains controversial. One reason for continued controversy is that most studies express results as relative risk/hazard or odds ratios based on P values that reflect diagnostic values poorly. Apo B and lipoprotein lipids were compared in 437 men. The results were evaluated by multivariate techniques and by receiver operating characteristic (ROC) curves. When analyzed by ROC curves, the difference between apo B and lipoprotein lipids proved to be less than would be anticipated from the odds ratios. Although, after adjustment, the difference was about 14% by odds ratios, ROC analysis showed only a small difference of about 1%. These data show that clinical studies should analyze the data using an absolute measure of risk such as ROC curves rather than just relative indexes. Such a small absolute difference may also explain discrepancies between studies.