Just after DrupalCon Sydney at the start of February of this year, I overheard some people wondering why they should sponsor a DrupalCon. Considering the people who attend, there's not a lot of product selling you can do if you're a Drupal shop and unless you're looking to hire delegates as new staff, there's not a lot of direct benefit from having a sponsor booth or table.
Obviously, helping to fund a DrupalCon and the Drupal Association via a sponsorship are good things to be doing for the community, but the payoff isn't necessarily immediately apparent. However, there definitely is one. There just hasn't been a metric for it, let alone a testable metric.
Most Drupal development is done by people in disparate locations around the world. They communicate via irc, email and the issue queue, but don't necessarily meet face to face.
We all know that face to face communication is far more efficient. The use of intonation, facial expressions and body language all make it much harder to misunderstand each other. Additionally, meeting face to face allows for social non-code interactions such as having breakfast, lunch or dinners, parties or just "hanging out", which all help build the team.
With a better team spirit and less misunderstanding between team members, I propose that there are fewer arguments (hissy-fits, if you will) between developers the more often they meet face to face. And the more sponsorship, the easier it is to run events and be able to meet face to face and have a good time.
My sponsorship metric then would be a decrease in hissy-fits per core release.
Since it's nice to measure something and have a larger number be better, I think a little bit of elementary algebra would give us the inverse release hissy-fit (RH-1).
Now there are only three things left to do, find a common name for the unit, give it a symbol and actually measure it over time :-)