In a survey study, a representative sample of individuals are asked to describe their opinions, attitudes, or behaviors. For surveys of behavior (eg, diet, exercise, smoking), authors should provide evidence that the survey instrument correlates with the actual, observed behaviors of a similar sample of individuals. That is, the survey instrument should have been shown to have validity. If the survey instrument is different in any way from that given to the previous validation sample (eg, wording, order, or omission of questions), then it may no longer be a valid measure of those behaviors.For surveys, as for other studies, it ...
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