Suggested answer to exercise: Checking student data, 6

Question 6: Calculate the standard deviation of the difference between the two measurements of head circumference.

Suggested answer

We can find the mean and standard deviation of the difference using Descriptive Statistics, Descriptives.

We get the following output:

Descriptive Statistics
N Mean Std. Deviation
difference 300 -.5033 12.78547
Valid N (listwise) 300

One decimal place should be enough here. Even that might be too much, as the first decimal place would be tenths of a milimetre. The standard deviation of differences between successive head circumference measurements = 12.8 mm.

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Last updated: 23 January, 2012.

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