How UK radio listening figures are worked out

Radio listener figures are produced by a company called RAJAR. But who is RAJAR? What does it stand for? And how do they compile the figures?

RAJAR stands for Radio Joint Audience Research and is the official body in charge of radio audience measurement for the UK. RAJAR was established in 1992 to replace two separate systems operated by the BBC and Commercial Radio. Today RAJAR collects information on behalf of over 300 stations, ranging from very small local services to the national networks.

Each week over 2,000 people are recruited by interviewers from Ipsos-MORI to complete a RAJAR diary. These people are chosen at random within carefully selected areas to ensure that the survey is completely representative in terms of the type of people who participate and the areas where they live.

This random selection process also ensures inclusivity as much as possible - non-listeners are recruited, while people with disabilities are encouraged to take part, with the help of a family member or carer if necessary. Ethnicity is also carefully monitored, with specific targets set to match the ethnic balance of individual areas.

Recruitment usually takes place over the weekend, and on the following Monday the selected respondents begin keeping a diary of their week's listening.

RAJAR uses a diary because it is the system that works best for the majority of people. There are two versions – a paper diary (that has been used for the past 20 years) and an online version (introduced in July 2011). The online version is seen as a complement to the paper diary and not a replacement for it because there are many people who still do not have online access.

The diary has separate pages for each day, with the day divided into quarter hour periods down the side of the page, and the respondent’s selected stations across the top to form a matrix. The respondent simply has to draw a line from the quarter hour when they start listening to a station until the time when they stop. In addition to the station and date/time, the diary also collects information on where the listening takes place (e.g. at home, in the car.) and the platform (e.g. AM/FM, DAB or Online).

At the end of the week, the interviewer calls back to collect the diaries they placed and these are returned to Ipsos-MORI for processing. This is repeated each week, and at the end of every 3-month period, the numbers are aggregated to produce individual station results. All stations use the information to plan programme schedules, while the Commercial stations also use the statistics to sell advertising airtime, without which they would cease to exist.

Across a year, over 100,000 people will participate in the RAJAR survey making it one of the largest media studies in the world.

The paper diary is the most common method of measuring radio audiences worldwide although some countries use electronic devices called audiometers. RAJAR has tested several audiometers and continues to work with developers to find one that matches its expectations, namely to measure all stations equally, regardless of size, format or means of broadcasting, at an affordable price.