I'm working on a case control study and the cases and controls are identified using a letter at the end of the identification number. Some cases are matched 1:1 with controls and some are matched 1:2, or 1:3. A case/control pair may be identified as follows: GI111A, GI111B, GI111X with A and B denoting control status and X denoting case status. I want to perform analyses comparing cases and controls and therefore want to make a new variable "case status" defined by the ending letter. Is there a procedure I can use to scan the identification numbers and then identify cases and control, respectively? I haven't tried any code yet, I was just wondering if there was a quick and easy way to do this?
You could use:
case = char(id,length(id)) = "X";
in a datastep, where id is your identifier. The value of case will be 1 for cases and 0 for controls.
PG
Would this create a new variable? Would I code it like creating a new variable?
Yes, the variable case would be created by the statement.You would use that variable in your analysis/models.
What if all my preceding numbers are not the same length? I'm still confused on exactly how to code this?
Please post the SAS code you are using now to prepare your data for analysis and we'll take it from there.
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