Abstract
The typical Type A evaluation of measurement uncertainty relates to the problem of approximating a constant from observations with independent errors. However, there are other realistic types of problem in which repeated observations x1 … xn might be obtained, most of which lead to different expressions for the measurement uncertainty. This paper identifies ten situations and presents relevant analyses, some of which are new. The results show that care must be taken to consider the nature of the measurand and the purpose for making the measurement.