1 Studies in the History of Statistics and Probability ... - Sheynin, Oscar

example, the problem of the objectively established risk factors. Tothese belong, on the one hand, portents of an illness established bymodern diagnostic means (e. g. changes in electro-cardiogram), on theother hand, factors of life and behaviour (age, smoking, amount ofcholesterol in the blood, etc). Since the business concerns someprecisely determined factors rather than vaguely understandableexcessive tempo of modern life, a scientific investigation of their part isin principle not unlikely.The possible ways of the development of the IHD are little known,so the statistical method of studying it is the main method. As usual,expectations here will be chiefly based on relying that a large amountof data will be able to compensate the deficiency of information aboutthe essence of the phenomenon (in this case, of the IHD). And sincethat disease develops gradually, over many years, it is desirable thatthe investigation covers not only a large number of people, but a verylong period of time as well (if possible, their whole life).A single examination of a large number of people presents seriousdifficulties; and, taking into account that people usually move severaltimes during their lifetime, you will understand that the real difficultiesare great. It ought to be also borne in mind that the relative number ofcases (of people finally developing the IHD) is rather small, so that thepopulation to be examined mostly consists of non-cases (other people).Therefore, the loss of a non-case by the researcher is comparativelyunimportant, but losing at least one case is extremely undesirable.However, if we allow the loss of people (for example, occasioned bythe man’s move or refusal to come for the examination), we do notknow whether it was a case or not and it should be attempted that thelosses be as small as possible, so perhaps the greatest part of the entireeffort is spent to attain that goal.The examination covered practically the whole population of asmall American town Framingham aged 30 – 62 years at its beginning.It is going on for more than 20 years and the cited source reports theresults of the first twelve years. They are based on investigating 2187men and 2669 women not suffering initially from the IHD. Itsdevelopment during those twelve years was revealed in 258 men(11.8%) and 129 women (4.8%); it was known long ago that womensuffer from IHD more rarely than men.The connection between the risk factors measured during the firstexamination and the probability of the development of the IHD duringthe 12 following years was considered. In general, it is possible to listrather many such factors, but only seven were taken account of:1. Age (in years). 2. Content of cholesterol in the blood serum(mm/100 millilitre). 3. Systolic blood pressure (mm of mercurycolumn). 4. Relative weight (weight expressed in per cents of man’sweight relative to mean weight for appropriate sex and stature). 5.Content of haemoglobin (g/100 millilitre). 6. Smoking (0, nonsmokers;1, 2 and 3, smoking less than a packet daily, smoking apacket and more than a packet). 7. Electro-cardiogram (0, normal, 1,abnormal).107