The official published membership statistics, such as those mentioned above, include only those who submit reports for their personal ministry; official statistics do not include inactive and disfellowshipped individuals or others who might attend their meetings. As a result, only about half of those who self-identified as Jehovah's Witnesses in independent demographic studies are considered active by the faith itself. The 2008 US Pew Forum on Religion & Public Life survey found a low retention rate among members of the religion: about 37% of people raised in the religion continued to identify themselves as Jehovah's Witnesses.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): Where do the officially published membership statistics come from?
those who submit reports for their personal ministry