Effectiveness and the Church

My job these days is being a Church Effectiveness Coach. What that means is that I spend my life with about 35 churches who are a part of the Western Canadian District of the Christian and Missionary Alliance, asking them how they determine effectiveness for their congregation and in their context and how they are then going about being effective.
The question I am asking at this moment is how I go about helping congregations define effectiveness?
Is effectiveness about some illusive "spiritual maturity" or is it about some form of growth (growth in weekend worship attendance, number of people who claim 'salvation', number of people who get baptized) or some other measure.
The CMA in Western Canada has chosen the measure of people who get baptized. The logic is that baptism is a very public measure of a person's inner commitment and one of the only really truly measurable spiritual growth or spiritual commitment indicators.
True it would be nice if we could get indicators from people's bosses or spouses or family members as to how their walk with Christ has impacted their life, but that is not practical. Baptism on the other hand is a way that a private inner commitment between a person and God is made public and a way that a person seeks both affirmation and accountability for their own spiritual walk.
My task is to help congregations and their leadership seek to discover ways to effectively lead people to a point of being willing to and wanting to make a public commitment to their personal spiritual walk and formation. Because baptism is not a part of congregational membership per-say, baptism is truly a way to make a public statement of personal faith.
So, what makes a church effective? And what needs to happen to become effective.
When I can nail those concepts down in a congregation, then great strides can be made towards being a church that is truly living out the great commission.
Hmmm...