1. Merge vs. Read and Append in Analysis
Apologies - the correct syntax to read multiple files in Analysis is:
read file1 append /file=file2
you can keep adding files.
SAVEDATA will save a new .rec file. This is especially useful if you have temporary variables that are used to manipulate the data. You can do this:
VAR DROP temp1 temp2 temp3 SAVEDATA finaldata.rec
Merging with Entry provides a bit of documentation of what was done and can be automated with EPIC (but thats another level of data management).
2. Merge and IDNUM. I normally avoid IDNUM as it is often useful to record ID numbers before you get to enter the data. However, you can use IDNUM and merge data successfully, if you assign each data entry person a unique range of IDs. In EpiData Entry, you can set an option for the first ID to use when entering the first record of a file. It is under File, Options and the Advanced tab. So one person could go with the default (1) and another could change this to 1001 before entering any data.
Another approach, where IDNUM was used and both sets of data start with 1 (although this is really not good data mangement practice, you might do this by including another code that indicates who entered the data). In this case, use Analysis to merge the data as above. Analysis doesn't care about unique ID numbers.
3. Field Epidemiology course and EpiData - we do a small field survey or observational study each year. We can send more info. Contact us via the e-mail address found at http://www.phac-aspc.gc.ca/cfep (Put my name in the subject line).
Jamie