I have a quick question. I need a sas code for this analysis and looking for your help. Hope you would help me. I have a monthly data of people receiving some service starting July of 2010 and forward until October 2013. As some are coming, some are leaving too. What I want to find is how many exactly are new comers to the program? My assumption is: For new entry: Anyone who has used the service in any of last 12 months, he is not a new comer. IF he has not used the service for last 12 months but seen to be using service this month, he is a new comer for this month. So, my analysis will start from 2011 July since I have a lag time of 12 months (and my data starts from 2010 July). So, I want how many are new comers every month to the program. For exit: Anyone who has used the service in last 12 months, but we do not see any service for next 12 months, then in the 13th month, we claim him as exit. This also has a lg time of 12 months. So, I want how many exit every month. Then I can add new comers and subtract exit to come up with some exact number of new recipients in the program. I hope you understand what I mean. Let me know if you can help me with coding for this issue. Also, let me know if you do not understand what I mean. I will be waiting for your reply. Thanks.
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