What is The Grocer 33 and how does it work?

The unique weekly combination of a price comparison survey with a nationwide mystery shopping survey provides The Grocer with real-time insights into how Asda, Morrisons, Sainsbury’s, Tesco, and Waitrose are performing, while regular guest retailer appearances from Aldi, Amazon, Iceland, Lidl and Ocado delivers additional tests.

The weekly data we collect to calculate the grocer offering the cheapest prices and the best service and availability every week is then collated into weekly reports that offer retailers and suppliers vital, independent insight. In addition we conduct an interview with the store of the week.

The weekly results also determine the results of three annual awards for price, service and availability. At the end of the 49-week period in which the surveys are conducted we award three Grocer Gold Awards by totting up the respective scores over the course of the year, while the store of the week winners are also put forward for the annual Store Manager of the Year competition.

How do you choose the products?

Every week we shop 33 identical or carefully matched and ratio-adjusted items including branded and own-label products, value lines and premium ranges, weighted to reflect consumption across the major grocery categories. The basket of 33 goods is refreshed weekly to ensure we’re checking a wide range of products over the course of the year.

How do you collect the prices?

Price collection is conducted online every Monday using Assosia’s price and promotion platform, which provides real-time analytics and powerful insights across all categories within the grocery sector. Some price collection also takes place in-store for verification purposes using their retail audit teams. You can contact Assosia or email services@assosia.com

How do you measure prices and determine the cheapest retailer?

Using pricing and promotion data collected by Assosia, we calculate the total cost of each retailer’s baskets using six different pricing methodologies: the base price; the display price; the multibuy price; the loyalty display price; the loyalty multibuy price; and the all-inclusive price. The winner each week is now determined using the loyalty display price (effective 2023/24). The Grocer 33 price comparison also tracks prices and price inflation (week on week, month on month and year on year) as well as promotions activity and other price measurements at an individual sku level to provide a complete picture of supermarket and product pricing strategies. You can check the latest winners here.

Why have you changed the way you measure prices?

Over the years we’ve enhanced the Grocer 33 in numerous ways to ensure it remains relevant and reflective of the latest market dynamics. The latest change is to the methodology we use to rank the cheapest supermarket every week. Informed by consumer research conducted by Toluna & Harris Interactive we now include loyalty prices in our price measurement. You can read a fuller explanation of the reasons for the changes in the explanation here.

Why don’t you shop the discounters more regularly?

The Grocer 33 list is refreshed weekly to ensure we’re checking a wide range of products over the course of the year. Due to the limited assortments of the discounters it is impossible to find a sufficient number of product matches without returning to the same items every week. You can find the latest Super 33s here.

Do you track discounter prices in any other way?

Yes. The KVI Price Tracker measures weekly retail price changes on key value items at Aldi and Lidl as well as Asda, Morrisons, Sainsbury’s, Tesco and Waitrose. We are able to do this as the 200-strong list of items does not change and does not require a product match across all seven retailers. You can check the latest reports here.

How do you measure customer service in the Grocer 33?

Every week our nationwide team of mystery shoppers visit supermarkets across the UK armed with the list of 33 items. Shopping surveys take place on either a Friday, Saturday or Sunday, with a pre-set two-hour time window on the predetermined day each week ensuring there is a level playing field between the shops. The mystery shoppers assess the car park, in-store experience, store standards, shop floor service and checkout experience, as well as checking the availability of the 33 items, noting which are out of stock and which are not stocked. The Gold award goes to the supermarket with the best service and availability over the 49-week period. You can check the latest winners here.

How do you measure availability?

In the course of the mystery shopper visits to the stores a separate tally is kept of supermarket availability. Each shopper checks the same list of 33 items, noting which are out of stock and which are not stocked. The Gold award goes to the supermarket with the best availability across the 49-week period, based on the number of full baskets and overall availability percentages.

Who are your mystery shoppers?

The Grocer has a nationwide team of mystery shoppers. These are ordinary shoppers but they selected and trained to ensure they provide independent assessments of customer service and availability.

Do you ever conduct online mystery shops?

Yes. Separate tests are conducted in a quarterly ‘Online 33’. This uses the same shopping list but features a different methodology, to assess areas such as website navigation and delivery. You can check the latest winners here but there are currently no awards attached to this service.

Are there any changes planned to The Grocer 33?

We are always looking to evolve the Grocer 33 to reflect market dynamics. We are planning a number of significant changes in 2024 kicking off with the new pricing methodology to allow loyalty pricing in our measurement but that’s just the start. Watch this space!