Exercise: Nuchal translucency, answer 1

This website is for students following the M.Sc. in Evidence Based Practice at the University of York.

Question 1: The standard deviation of intra-operator difference was 0.35 mm. What exactly is this standard deviation? How does it differ from the within-subject standard deviation?

This is the standard deviation of the differences between two measurements made by the same operator. The within-subject standard deviation is the standard deviation of differences between repeated measurements on the same subject. The standard deviation of intra-operator difference is equal to the within-subject standard deviation multiplied by root 2.

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