Читать книгу The Pocket Guide to Critical Appraisal - Iain K. Crombie - Страница 11

Surveys are often used to estimate how common something is: how many people have high blood pressure, or how many suffer from chronic pain. They can also investigate associations between factors: is it more common in men or women; does the frequency of high blood pressure vary with age? Surveys can study whole populations; for example, to establish the proportion of people who currently smoke cigarettes. Or they can investigate specific groups; for example, they could explore the health beliefs of pregnant women, or the frequency of loneliness in persons aged between 65 and 90 years.