With the WTS, numbers are either about control... or about damage control. Therefore, some of the numbers are precise, others are not.
willyloman hit the nail right on the head in his post. The organization is statistically driven. These numbers are looked at by traveling overseers, and then are discussed in the Circuit Assembly "Giving Attention to the Needs of the Circuit" talks. I remember the last Circuit Assembly I went to in November 2005, the District Overseer gave a lengthy commentary on the attendance figures for the circuit. He proceeded to tell the assembly that their numbers were considerably lower than those of the Spanish; and that they should be more like the Spanish brothers. It was like sitting through a sales meeting for Coca-Cola; hearing an executive lament the fact that Pepsi was selling more.