Question 8: What assumptions about the data are made for the calculation of the limits of agreement?
The limits of agreement are calculated from the mean difference minus or plus 1.96 standard deviations. We must assume that the mean and standard deviation of the differences are constant so that we can estimate them. They should not be related to the magnitude of the glucose. The 1.96 comes from the the Normal distribution. We must assume that the differences follow a distribution which is approximately Normal, or at least symmetrical.
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