First of all, if leaders are tracking membership as the key indicator of their church's health, they are tracking the wrong thing. Worship attendance is the most accurate, and immediate, barometer of a church's health.

But what if worship attendance begins to decline? What's the diagnostic procedure?  Here are three key numbers to research:

1. Visitor Volume. The obvious but often overlooked fact is that churches need visitors to grow. Specifically, a church needs four to five percent of its average annual weekend attendance to be visitors (first, second, or third time). You may have excellent music, enlightened preaching, a great children's program, and a wonderful facility, but if you don't have enough visitors, your church won't grow. 

2. Visitor Retention. This is the answer to the question: "Of the people within our ministry area who visit our church, how many stay?" The average non-growing church has a visitor retention rate of nine percent, which means that nine out of every 100 are ...