[EpiData-list] forcing 3-digit id numbers

epidata-list at lists.umanitoba.ca epidata-list at lists.umanitoba.ca
Fri Feb 15 10:21:55 CST 2008

I am using a unique ID for individuals in a study. The ID must be 
between 001 and 150 and it is a 3-character string field to ensure 054 
is entered, for instance, rather than 54.
Certain numbers can be entered with fewer than 3 digits without 
generating an error message.   Without trying every possible 
combination, it seems that these numbers are 1, 10, 11, 12, 13, 14 and 
15. The thing that these seven numbers have in common is that they could 
all be extended to 3 digits by filling in only zeroes, and still meet 
the criteria for the field (100, 100 again, 110, 120, 130, 140, 150).  
160 is too big for the range, so 16 generates an error message. 200 is 
too big, so 2 is not allowed. This is just a guess to explain why these 
seven numbers slip through the filter.
If I'm right, is there anything I can do about it? If I'm wrong, what's 
the explanation?
Thanks for your help,
Vicky Simms

King's College London

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