Leading Articles depression of the ST-segment, or flattening or inversion of the T-waves were found to have a slightly greater predictive value than the majority agreement of the three cardiologists. The practical value of epidemiological studies is that from time to time they uncover clues about the aetiology of a disease which suggest means of controlling it or, at least, of modifying its course. With regard to control of coronary disease, they have shown that we must give up smoking, eat

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... , and take more exercise. Evidently we must also make sure that two out of three cardiologists agree that our E.C.G. is normal.