3 Why was an omnibus survey used?

AIR MILES, founded in 1988, is the pioneer of customer loyalty schemes.
Although hundreds of loyalty schemes have been introduced subsequently, including, more recently, online schemes, AIR MILES remains the UK’s leading brand in this market, with 6 million customers and 90 per cent awareness of the brand among its target audience – ABC1 adults aged between 25 and 54. The company has built up its business by forming partnerships with well-known companies through which customers collect AIR MILES.
The Who Joins Wins campaign was developed by ad agency Bartle Bogle Hegarty (BBH). Anybody who joined the AIR MILES scheme during the campaign was entered into a prize draw, and was guaranteed a prize, ranging from a cinema ticket to 1 million AIR MILES. The marketing objective was to increase new registrations by 250,000 during the campaign.