Notes and sources for Warc's global media costs data can be browsed by year (Excel format).
Users of the data should take particular note of the target audience definitions. For example, in most countries 'adults' will be defined as individuals that are over a certain age, perhaps 15 or 18. However, in some countries, the standard definition includes an upper age limit so, for example, the Canadian data are based on adults aged 25 to 54. Any narrowing of the audience definition will reduce the size of the audience and therefore increase the recorded cost per thousand figure.