The file res0102.sav contains measurements made from one another by a group of biomedical science, medical, nursing, physiotherapy, and radiography students. Each measurement was made twice, by different observers.
Download the file and read it into SPSS.
1. Using SPSS, look at the frequencies for the head circumference data. What two characteristics of the data does this reveal?
2. Draw histograms of the head circumference data. How does the information revealed compare to that shown using frequencies?
3. What could we do about the problems with head circumference?
Check suggested answer 3.
4. Try a tabulation of the first observation of the subject's sex against the second.
You can do this using Descriptive Statistics, Crosstabs.
What do you notice about the data?
Why do you think it happened?
5. Returning to the head circumference data, delete the invalid observations. Now compute the difference between the two measurements of head circumference.
6. Calculate the standard deviation of the difference between the two measurements of head circumference. We can use this in the study of measurement error.
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Last updated: 18 October, 2006.