Comparison group question

[Jennifer Taub <jtaub@xxxxxxxxxxx>]

Hello there:

I am conducting an evalution of a drop out prevention program in a high
school.  Kids are referred to the program through a school
educational team to which high risk kids are referred. We are
also gathering data on a comparison group of kids who have been referred
to the team but do not enter the Drop out program because there are no
openings, or becuase it is not thought that they are a good fit for what
the program has to offer.  The Program kids are matched on a kid-by-kid
basis by gender, age, and school history (i.e. disciplinary referrals,
truancy, drop out).

Here is my question:

Some of the kids in the comparison group may, at some point in the future
(say, next school year) end up in the Program as room is available. (Most
of the kids in the comparison group will never end up in the Program).
What to do with these kids?  Should they be dropped from the comparison
group if they enter the program?  Should they be placed in a third group
and serve as their own controls?

Any help with this dilemma is appreciated!

Thanks!  - Jennifer Taub, University of Vermont