Hi!
I see that you used the Merge statement. There are a lot of different issues to consider when you are using a merge. For example, a merge by ID and Place would be entirely possible and depending on your data, might give you different results than just a merge by ID. The data step merge works best, in my opinion, if you are doing one-to-one or one-to-many merges.
You can control which variables come from which dataset by using the (DROP=) or (KEEP=) data set option in your Merge statement. You can further control your processing by using the (IN=) option for each data set -- because it will give you a variable name to test in an IF statement.
Describing everything you need to know about how MERGE works could take a LONG time. I suggest you look up MERGE in the documentation and/or consult some of these user group papers (listed below) or contact Tech Support for help. One technique that works really well for me is to create several small data files, which would allow my code to test all the possible combinations of the data, then once the test data is combined correctly, I know how my MERGE is going to work and I point my program at the production data.
cynthia
** some papers **
http://support.sas.com/techsup/technote/ts644.html
http://www2.sas.com/proceedings/sugi28/096-28.pdf
http://www.ats.ucla.edu/STAT/sas/library/nesug99/ad155.pdf