Measuring the success of a documentary?

There are paid services that will monitor mentions of the story, but other than a rough count of airings, I don't know that they can give you an objective or even subjective analysis of how effective the doc was. For that, the doc needs to have some clear call to action, as in "sign this petition" "call this number" "Don't buy product X this week"or "visit this web site". You know, having the audience physically DO something that can be polled or counted.

I think you probably should have set up a deal with a polling company to survey the audience before and after. Doing that now, without the "before" picture is unlikely to be very reliable, IMO. This measuring function should have been thought of before the doc was released. Now your best bet may just be a head count of people who saw it.