Karen Halligan is the CEO of OzTAM, the company that measures Australian television audiences. OzTAM is independent, but is owned by three fierce rivals: Tv networks Nine, Seven and Ten.

This week OzTAM changed the way audiences are measured in Australia, bringing it into an age of catch-up viewing and online streaming. Karen Halligan talks to Sean Aylmer about the changes, and why it matters to TV networks, advertisers and audiences.