Media not Mediums
As someone who actually majored in Advertising in college, I've been studying this stuff for a long time. Of course, it's ironic that there's many in our industry who majored in everything from Chemical Engineering to Art History who know more about Advertising than me. However, one benefit of a formal advertising education is poise with the vernacular.
Say This: "Our analytics platform is capable of measuring ROI across many different media"
Not That: "Our analytics platform is capable of measuring ROI across many different mediums"
Media refers to online, tv, magazine and newspaper communications vehicles. Mediums refers to the gathering of 2 or more people channeling the dead.