THEY have been billed as a way to ensure that consumers are getting the best deal, wherever they do their shopping.
But a report has claimed that at-checkout price comparison vouchers are more likely to come out in favour of the store that is doing the check than any of its rivals.
An investigation by Which? found that individual schemes which claim to give shoppers a compensation voucher if their shop would have been cheaper elsewhere differ greatly between stores.
Asda, which runs the Price Guarantee scheme, was cheapest almost 90 per cent of the time, according to its own comparison, while Tesco’s Price Promise and Sainsbury’s Brand Match claimed to be cheapest for half of the 20 shops carried out at each chain.
“Supermarkets each set their own rules for what is and isn’t compared, and sometimes stock products in different sizes, so it can be hard to tell who’s the cheapest overall,” said the Which? report. “We examined 59 different shopping trips made by ordinary shoppers, and found the ‘cheapest’ supermarket was often the one running the comparison.”
While Asda and Tesco include both branded items and equivalent non-branded products, Sainsbury’s only includes branded foods in its comparison. There is also a discrepancy in the minimum spend a customer needs to qualify. At Tesco, ten items are needed, while at Asda the minimum is eight and at Sainsbury’s, it is £20.
Earlier this year, Dalton Philips, chief executive of Morrisons, hit out at Tesco’s Price Promise scheme, claiming that a third of the comparisons with its own products were unfair.
Morrisons’ own research found that Tesco had struggled to compare fresh own-brand produce such as fruit and veg – often ending up discarding almost a third of the basket as not possible to compare.
“We find it challenging when a third of the basket is not successfully compared,” said Mr Philips at the time. A spokesman for Morrisons, which does not operate a price comparison scheme, yesterday added: “We are not surprised by the Which? report.
“It clearly points out that they can’t all be the cheapest and highlights a problem with these price comparison schemes.”
Just a month earlier, Sainsbury’s also attacked Tesco’s scheme over adverts which claimed that customers “won’t lose out on big brands, own-label or fresh food” if they shopped at Tesco.
However, the Advertising Standards Authority decided not to uphold Sainsbury’s challenge that the claim was misleading in relation to the own-label and fresh food items, because it did not take into account product attributes such as provenance and ethics.
A spokesman for Sainsbury’s said: “The principles on which Brand Match operates are very clear to customers, and this simplicity is one of the reasons they love it.”
Tesco and Asda refused to comment.