In membership metrics, retention rates rule the data set.
Without retaining Rotarians everything else is irrelevant, including attracting and engaging new Rotarians. Engaging is a means to an end, and the only effective measure of engagement's success is how many become and remain Rotarians.
Retained Rotarians, by word of mouth, usually attract and engage potential Rotarians. But let's face it: clubs can have high numbers of Rotarians and friends engaging in activities. Does that mean that the Rotarians will remain; that friends will want to join a Rotary club? Maybe. It all depends on how the benefits of engagement relate to the engager's needs and priorities, including the cost in time, talent, and/or treasure. The same fundamental principle applies when groups consider engaging with Rotary International. Without question, retention rates rule when it comes to measuring clubs, districts, zones, and Rotary International's effectiveness at engaging Rotarians in advancing the Object of Rotary.
All interactions between Rotary International, Rotary clubs, Rotarians, and potential Rotarians should be based on the concept that