One way to measure the effectiveness of MO is to track how often it leads to publishable research. That angle has been discussed before.
I'm wondering if there are other metrics that can be used to assess the effectiveness of MO. For example, how many questions get asked? How many get answered? Has this changed over time? Is there any evidence that "soft" questions have a beneficial effect by attracting more users, who then see the "hard" questions—or is there any evidence of the opposite, that "soft" questions cause users to abandon MO in disgust?
If there aren't such metrics, is there a way to create them? Or perhaps it's a bad idea to create such metrics, because they will be misinterpreted, leading to bad side-effects?