Let's see: considering that their target audience here are very vulnerable emotionally...
Only 15 studies??? (These can't really be counted as studies until the THIRD study, so I'm thinking they got 15 people to give them their contact info to be called on at a later time. I doubt these are ACTUALLY studies.)
Essentially, only one in 13 of those 200 JWs got someone to give their contact info.
And only 4(ish) visits per cart. (EDIT: probably a lot more visits than this, but only 4 per cart who gave contact info)
While higher than normal results, keep in mind the emotionalism of the event.