Take a look at You Learn Something New Every Day – Gillian’s post By The Numbers: The Power of Math in Group Processes makes an interesting read, and a timely reminder that we’re not always doing a group a favour if we bow to pressure for more plenary sessions.
I’ve also found myself using maths to justify facilitation decisions. I have had meetings of 50+ people suggest a go-round to hear about the various campaigns and projects other people are involved in. These can be very interesting and affirming for groups, but given that people can rarely summarise a project in less than 2 minutes, and some will need significantly longer, well do the maths. Is it realistic to expect people to sit for over an hour and a half? What’s the quality of the listening like for the second half (or more) of the go-round? Do we run out of time with some people yet to speak?
Of course it’s not all about plenary sessions. I also like the thought of numerically articulating the time that’s being invested in a process. It’s good to make these things explicit.