Biology · Organisation. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Health is a state of physical and mental well-being. A communicable disease is caused by a pathogen and can spread from one person to another. A non-communicable disease cannot spread: examples are coronary heart disease, type 2 diabetes and most cancers.
In coronary heart disease, layers of fatty material build up inside the coronary arteries and make them narrow. Less blood reaches the heart muscle, so it gets less oxygen.
A risk factor is something that makes a disease more likely, such as smoking, a poor diet, too much alcohol or too little exercise. A link in data is a correlation. It does not prove cause on its own.
Students say that a correlation proves that one thing causes the other. Data alone show a link; a cause needs a known mechanism and other evidence.
Answer: The risk was 3 times greater for the smokers. This shows a correlation with smoking.
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