if you are familiar with mis the church's membership database you'll notice that when they reach the age of eight they are removed from membership roles if they are not baptized within their eighth year however if their parents are still members their names are kept in mis not as members but part of a family who has a member with the parents until they are non baptized spouses are also included if i remember the designations for these are child of record unbaptized and non member they used to have an unaccountable designation as well for those with disabilities who don't need to be baptized although i've not seen it recently no unaccountables in my last ward that i'm aware of and they'd also be included with child of record in my opinion church statistics are more accurate than most other denomination's estimates and the computer system designates and distinguishes quite easily the catholic church for example bases theirs on country statistics if a country is deemed catholic then percent is counted as being catholic even if they are not or if they have had their names removed see this recent thread and resulting discussion