The Advertising Standards Authority has banned a price comparison advert from Tesco - following a complaint from Asda.

The ad outlined offers on a leg of lamb, fresh vegetables and pizzas.

“These are just three of the hundreds of special offers in store each week, to help you spend less each week,” it claimed. “And when we compared prices with Asda’s on 30 January, shopping was cheaper for over 1.1m Tesco customers.”

Tesco baskets were then shown with a graphic saying “1,150,000 cheaper” – alongside Asda baskets captioned “940,000 cheaper”.

A footnote added: “To verify, contact Tesco Price EN8 9SL or”

Asda claimed Tesco had not offered an appropriate means of verification for the comparison.

When Asda asked for the verification data, Tesco sent it the methodology, a list of matched lines and a list of 380 baskets they selected at random, showing the contents of each basket.

Tesco claimed the 380-basket sample was statistically significant and representative of the two million baskets it analysed. However the ASA said Tesco should have disclosed the full data for analysis by Asda. As Tesco only supplied a sample, ASA ruled the comparison was not verifiable.

Tesco was banned from running the ad again and told that in future it must provide consumers and competitors with the full data set for comparative claims for the purposes of verification.

Read more
ASA chief exec Guy Parker: In the hot seat (analysis; 13 August 2010)
Tesco ad campaign celebrates quality of own-label lines (2 July 2010)
Tesco taken to task for ‘ambiguous’ basket ads (30 June 2010)