Covert strings to numbers, then add total

Covert strings to numbers, then add total

OK, I'm a moron. I've just spent 4 hours trying to figure out how to convert several strings to corresponding integers, then add them up for a total. Sigh. I'm sure it's painfully simple, but I just don't get this scripting stuff.

Pretend I have Judge1 and Judge2, and each goes to an already existing data record to vote on the proposal contained within. Each has a field with their name on it, and a set of radio buttons with 3 choices-- "Bad", "OK" and "Great". When Judge 1 selects "Great" I need to convert it to the number 3. When Judge 2 votes "Bad" I have to convert it to a 1. Then I need the total, 4, to populate a formula field.

Does anyone have a few minutes to enlighten me? Before I jump out the window?