[R] Matching patients

[Bill Hyman]

May I ask a clinical question? For a trial, we have a treatment group of small 
size, say 30 patients. We want to selectmatching control patients from a bigger 
group (100 patients) in terms of several clinical variables, such as age, tumor 
stage etc. This practice is to select the closest matching set of control cases. 
I wonder if R has any routine or package that can help with this problem. Thank 
you. Looking forward...