One very efficient approach for overview of consistency. E.g. counts of id numbers at various times is to use the "count by id" function in document menu of EpiData Entry. (or for batch procedures with EpiC).
The idea is to count in different files how many times a unique identifier was found:. Example output:
Count of records based on field ID
Selected files: File 1 = key.rec File 2 = data\idkey.rec
120 different values for ID found
Files ID 1 2 --------------------- 0 1 1 1 6 6 2 6 6
The key variable could as here be a simple integer, but could also be a string, e.g. of the type: 0-1 0-2 0-3 constructed as a combination of the id (here 0) and the time of visit (here either 1 2 or 3).
In the check file: id mustenter end
timevar comment legal 1 "Initial visit" 2 "6 months follow-up" 3 "2 year follow up" end mustenter after entry idkey = string(id) + "-" + string(timevar) end end
idkey key unique noenter end
......................................... Notice that the "key unique" status for idkey is checked at creation of the contents, that is in the "after entry" block of the time variable.
regards
Jens Lauritsen EpiData Association