Sample and population

Some manuscripts are based on a detailed description of a series of patients and have a conclusion restricted to what has been observed. This is what could be expected of a case-series report. However, the same patients could also have been considered a random sample drawn from and representing a greater population of patients, perhaps including future ones. In this case, the findings cannot be directly generalised to the greater population because of sampling uncertainty. When attempting to describe the underlying parameters of the population (including the sample), the uncertainty needs to be presented. This is what p-values and confidence intervals are used for. The inclusion of these measures in a descriptive report, written without any ambition to evaluate underlying mechanisms or effects, indicates methodological confusion.

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