The key measure of readership is known as Average Issue Readership or AIR.
AIR is the number of people who have read or looked at an average issue of a publication.
The definition is based on those who say they have last read a publication within its publication interval, i.e:
|Daily newsbrands||Read yesterday|
|Sunday newsbrands||Read in the last 7 days|
|Weekly magazines||Read in the last 7 days|
|Fortnightly magazines||Read in the last 2 weeks|
|Monthly magazines||Read in the last month|
|Bi-monthly||Read in the last 2 months|
|Quarterly||Read in the last 3 months|
For daily newsbrands AIR is available for Saturday editions, as well as an estimate for the 5-day weekday edition, and an overall 6-day estimate. The 6-day estimate is a modelled figure and should be used rather than manually combining estimates for Saturday editions and 5-day weekday editions.
To qualify as a reader, the publication must have been read or looked at for at least 2 minutes. In fact, publications are read for much longer than this, as the time spent reading data show.
There is also a great deal of other information about readership available from NRS.