Hi Patrick, I am doing the same thing as you. I tried different examples and find out that: if the original data has a missing value, as the example you gave(1,2,9, and .), then there would be no problem, '9' will be given to missing. if the original data doesn't have missing value, as the example I gave (1,2, and 9), then '9' will be given to ' ' in the frequency table.
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