Yep, pretty sure you've got it. What kind of visual are you going for with it?
With a sample file, it would be easier
Here is how I would do it:
(IF [Name]='Jim B.' THEN AVG([Measure 2013 Score]) END)
AVG([Measure 2013 Score]
AVG([Measure 2013 Score])
Darren, if you use Fixed clause with Student as dimension in your calculation you'll keep the total value ignoring student filters.