Question 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?
We get the table by Descriptive Statistics, Crosstabs, then choose variable sex 1 for the row variable and sex 2 for the columns variable, OK.
We get the following output:
|sex 1 * sex 2 Crosstabulation|
Three students seem to have changed sex during the measurement exercise.
This is very unlikely. There are several possibilities:
We do not know which is the correct explanation, but I suspect explanation 4 to be correct.
The same thing happened every year that I ran this exercise. It shows that we cannot assume that data on a computer file are correct. Checking is essential.
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Last updated: 20 October, 2006.
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