I have always felt that the Society is basically honest in compiling and publishing their statistics. The reason I believe this is because of the Anointed numbers: the fact that this number went up again, as it usually does, looks real bad. It proves that Jehovah is either a poor judge of character, or that the whole doctrine of a diminishing anointed remnant is a big crock. It's one or the other, pick one. If the Society was going to lie about their stats, then I would think that they would lie about that one. And it would be real easy: Just report a 1% or 2% decrease every year and they could go for decades and no one would be the wiser. But when it shows an increase, then they report it as such.
So I think that the society is basically honest with their numbers.
Well - not necessarily so anymore, since this increase in partakers has been dealt with by "new light" this year. It's not necessarily expected to decrease anymore, actually I guess it's now expected to increase (which it has and will). That's the effect of "opening heaven up again", and allowing new anointed, which again they had to do in order to "stretch time" (or buy time), since the 'original' anointed were dying out and some anointed are supposed to live when Armageddon comes. That, and that "this generation" is now the anointed as a group.
But it will be interesting to see how they'll deal with it if it suddenly increases to 144.000 or more, as was mentioned above... There's really nothing stopping that from happening now, because they don't know the global number of partakers until they add them all up from the reports. Each congregation doesn't know how many there will be globally, so they can't really stop people from partaking either. So... perhaps one last desperate "new light" will eventually be that all JWs turned out to be so good and true, that they're all going to heaven(!). But more likely, the 144.000 will then suddenly become a figurative number instead of literal, I guess.