"2) I understand that the dropout rate for JWs who've been converted is like 2 out of every 3. Does anyone know if there's a statistical dropout rate for born-ins?"
Well, the Pew study linked to doesn't really give much info on the retention rate of converts -- it gives info on the retention rate of those raised around the religion. But just from my reading of various research on NRM's, the retention rate among converts to NRM's is actually quite high (between 60% and 80% on average).
They did show that the makeup of that small, 215 person sample was as follows though:
Jehovah’s Witness: 33% raised Protestant; 26% raised Catholic; 1% from all other faiths; 8% raised unaffiliated; 33% non-convert (raised as Witnesses) =100%
So that "37% retention rate among those raised as Witnesses" figure that they came up with is actually not even based on 215 people. It is based only a total group of about 71 non-converts (which makes the number even less statistically significant).
The make-up of the group also explains why the Witnesses have not just completely fallen apart and disappeared from the face of the earth yet (as you would expect any group to do that only retains 37% of members). The Witnesses are not losing 67% of their TOTAL membership, they are losing 67% of 33%, which is only about 22% overall. Combine that with the high convert ratio (68% converts) and factor in a much larger retention rate for those converts, and you can see why the Witnesses are still growing at a faster pace than most of the other religious denominations.
But of course, we are still only basing all of this on a survey of 215 people. If we had a few thousand, then yeah we could put more faith in the numbers. But as it is we have to take them with a grain of salt.
=edit=
Been poking around for convert retention rate info, and found this blurb:
It is a matter of grave concern that the areas with the most rapid numerical membership increase, Latin America and the Philippines, are also the areas with extremely low convert retention," says Stewart, a California physician. "Many other groups, including the Adventists and Jehovah's Witnesses, have consistently achieved excellent convert retention rates in those cultures and societies Latter-day Saints lose 70 to 80 percent of their converts, while Adventists retain 70 to 80 percent of theirs.
http://www.sltrib.com/ci_2890645
Here is another site discussing the Pew surveys: http://www.cumorah.com/index.php?target=church_growth_articles&story_id=14
The Jehovah's Witnesses, on the other hand, reported a net gain, with converts outpacing the children of members lost to disaffiliation. To put it another way, 71% of individuals presently identifying themselves as Jehovah's Witnesses were converts, compared to just 23.5% of Latter-day Saints... The Pew survey documents that the LDS Church is significantly more successful than Jehovah's Witnesses at retaining (at least in the sense of retaining self-identified religious preference) individuals born in the faith, but is much less successful at retaining baptized converts... In contrast, the Jehovah's Witness proselyting program has been substantially more effective when assessed not from the angle of raw baptismal statistics, but from the perspective of making and retaining adult converts who continue to affiliate with the faith and constitute the bulk of its committed membership. The Witnesses' own annual statistics consistently demonstrate retention of 55-65% of baptized converts worldwide, more than double LDS convert retention rates.
