My calculations

I was asked about the numbers in activity used in an earlier post. (Sorry no link, the moderator can't remember which one) That calculation was one I made based on the statistics we were given by the Mission President on our area.

By way of background, I did a two year stint as the Ward Mission Leader, followed by five years on the High Council over missionary work in my stake. During the last two years on the High Council we would meet quarterly with the mission presidency.  During those meetings we would be updated on the numbers throughout the mission and the church.  The numbers worked out to approximately 37% activity rate church-wide.  HOWEVER, the definition of "active" included anyone who attended a single sacrament meeting during a quarter.  This had the effect of inflating the number by all those who attended during Easter and Christmas (because they all became instantly "active" during two quarters of the year).  They also were affected by the count of sacrament meeting attendees who came for missionary farewells and missionary homecomings.  

I did a count of my own to try and come up with a "distortion" number to attempt to calculate who was really carrying the load as an average.  I couldn't get a consistent result using my own ward to allow for Easter/Christmas and missionary farewell/homecoming additions.  But it appeared to me the distortion was somewhere between as little as 5% and as much as 10%.  I took a mid-point between the two and made my overall estimate of 4,000,000 out of the total church membership as those who are really serving regularly, attending regularly, and who are not merely "active" by virtue of quarterly appearances in a sacrament meeting.  I hope that serves your purposes.