ILoveTTATT2: If the average of the 1970 group is 20 years (i.e. most left in the
90's), and the average of the 2000's group is 10, meaning most left in
2010, then the statement that the exit is speeding up is valid.
No it is not. Your conclusion does NOT follow from your premise.
If you would have somehow been able to conduct a similar survey of the 1970 group in 1985 you would have gotten an average much lower than 20 years due to the fact that you were surveying a 15 year time period. It could not have been longer than the period under consideration.
I suspect the relatively large percentage of those leaving after the 1975 debacle would actually have made the average Length of Time a JW for the 1970 Group much lower. But you are asking people forty years later. It's no coincidence that the average time a JW now is 20 years:
- (2015 - 1975) / 2 = 20 years
-
It would be more telling to try and determine what percentage of people leave the religion each year and has that trend changed.
Again, please see my reference on the previous page to Paul Grundy's work and read his detailed study. You'll find it most informative.
A few years ago, the Pew Forum posted a study that showed that JWs had the worst retention rate of any religion in the United States. But it did not account for converts, only born-ins.
Pew Forum survey - Key Findings and Statistics on Religion in America (note this link goes to an updated analysis of the 2007 report referenced below):
Jehovah's Witnesses have the lowest retention rate of any religious tradition. Only 37% of all those who say they were raised as Jehovah's Witnesses still identify themselves as Jehovah's Witnesses. - (From a nationwide survey conducted from May 8 to Aug. 13, 2007)