New research has found that for every £1 advertisers spend on online display ads delivers an average of £1.94 in sales in the supermarkets.

The study, involving the likes of Unilever, Nestle, Nectar and the IAB UK, looked at a series of online display ads through mobile and desktop websites (Guardian, Yahoo!, eBay, Gumtree) which reveal the degree to which online display ads drive sales of popular household brands both online and in-store.

Ads for nine brands – Nescafé, Häagen Dazs, Persil, PG Tips, Magnum, Surf, Maille, Tropicana and Aquafresh – were tested across mainstream desktop and mobile sites including The Guardian, Yahoo!, eBay, Gumtree, AutoTrader and Mail Online. The purchasing behaviour of those who received the ads was then compared to those who didn’t using a combination of Nectar loyalty card data – providing transaction data for over 12 million Sainsbury’s customers – and Nielsen Homescan data, which measured shopping behaviour at other UK supermarkets.   

Proving ROI

“The ‘Holy Grail’ question we get from marketers is what impact does an online ad have on offline sales, and the answer is a very big one as the vast majority of the sales attributable to the online ad happened in-store,” commented Tim Elkington, chief digital officer at the IAB UK in response to the research findings.

Interestingly, all the ads carried a Sainsbury’s logo which Elkington added illustrates the “halo effect” that store-branded advertising can have on sales in other supermarkets. The IAB conservatively estimate that these co-branded ads are 21% as effective at driving additional sales at a different supermarket as they are at Sainsbury’s.

“The calibre and range of the brands involved in the project gives marketers a reassuring guide as to what their investment in digital will pay back.” said Elkington.

This is further based on the fact that 55% of shoppers believe that an ad carrying the Sainsbury’s logo means the product would be available in other supermarkets, while 38% said the Sainsbury’s logo would make no difference to which supermarket they purchased it from.