If someone would like to launch a mass-media campaign on the internet (website) for public awareness regarding a specific topic. How can we measure effectiveness of such campaign?
A campaign on internet - I would look both at the amount of individual visitors in a certain time period - and the time the individual visitors spent on the page.
You should include some sort of an outcome measure based on what you which to accomplish; is it knowledge about an issue? If so perhaps you could include a short questionnaire that people might solve.