RAJAR
Radio Joint Audience Research Ltd was established in 1992 to operate a single audience measurement system for the radio industry - for more information visit www.rajar.co.uk

Housewives
Main shopper - not specifically female

IR
Independent radio or commercial radio services

TSA
Total Survey Area, also known as the broadcast area or marketing areas of a station used as a basis for audience measurement

Reporting Period
Depending on the TSA of a radio service, different sized stations report using different quantities of survey data, Quarterly (3 months), Half-Yearly (6 months), Yearly (12 months)

Listening
Audience listening is recorded in 15 minute segments and is defined as at least 5 minutes listening within a particular segment (between midnight and 06:00 listening is recorded in 30 minute segments)

Average Hours
The average length of time spent listening to radio, or to a particualr station, calculated as Total Hours divided by Reach = Av. Hrs.

Share of Listening
The percentage of total hours listened to radio that is accounted for by a particular station

Reach (000's%)
The number of different people within the target audience who will hear at least one advert from a campaign

Impacts Gross Impressions)
The total number of exposures to a schedule of adverts; not a measure of the number of different people exposed to a commercial; calculated as Reach 000's x OTH

Radio Ratings
Impacts expressed as a percentage of the population group being measured; calcuated as (Impacts x 100) divided by Population = Rating

OTH (Frequency)
Opportunities To Hear, the average number of times the audience reached by the spot schedule is exposed to a commercial; calculated as Impacts divided by Reach = OTH

CPT
Cost per Thousand is the most basic term used to express Radio's unit cost. Most frequently used to compare the cost of 1000 impacts on different stations; calculated as Schedule Cost divided by Impacts = CPT

Cost Efficiency Factor
Representing the value of a station in reaching a specific target group. CEF is expressed as a CPT and is calculated as (CPT x Adult Hours) divided by Target Hours