For many years, advertisers and marketers have been calling for a single source audience measurement approach. 
For industry currency measures of main media, including radio, TV, print and out of home we need to turn to an array of peak industry associations- each developing their own unique measurement tools and techniques in conjunction with their preferred media research suppliers. The emergence of new media platforms has triggered demands for new measurement methods. This article, is the first part of a two part piece on media metrics. The present article reviews recent changes to existing media metrics.  In part two, the case for new metrics will be presented.