Understanding the Rate of New Cases of Coronary Heart Disease
Explanation:
To calculate the rate of new cases of coronary heart disease among the observed group, we divide the number of individuals who developed the condition (81) by the total number of individuals observed (617). This division gives us a rate of 81/617 = 0.131, which represents the rate of new cases per man observed per year.
However, rates are often expressed per 1,000 individuals for easier comparison and interpretation. To convert the rate to cases per 1,000 men per year, we multiply the result by 1,000. Therefore, the rate of new cases is calculated as (81/617) Ã 1000 = 131.28 cases per 1,000 men per year.
In epidemiological studies similar to the one described, terms such as the population, sample, experimental units, explanatory variable, treatments, and response variable are of importance. These terms help in structuring the study, clarifying objectives, and defining methodologies. For instance, the population in this case could refer to men aged 50 to 84, and the sample would be the 400 men who participated in the study.