ryanpetrello/cleaver — pull request #7 by ewheeler (2013-07-24 20:45:35+00:00)
Title: return 'Invalid' instead of raising exception

in rare circumstances (when conversions greatly outnumber participants), a ValueError is raised when attempting to calculate a z-score. this makes the web interface unusable.

this code checks for invalid experiment data and returns 'Invalid' before attempting the final z-score calculation