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How we survey supermarket grocery prices

Our nationwide survey of grocery prices reveals which supermarket offers the greatest savings. Here's how we do it.

Last updated: 02 July 2024


Checked for accuracy by our qualified fact-checkers and verifiers. Find out more about fact-checking at CHOICE.

Housing costs aside, the bulk of Australians' hard-earned cash goes towards buying groceries.

CHOICE research shows that the vast majority of people continue to be concerned about their food and grocery expenses, with our March Consumer Pulse survey finding almost nine out of 10 households are worried about the cost of groceries. This level of concern has remained consistently high since March 2022. 

So we've made it our business to find out where you can buy the cheapest groceries. Here's how we do it.

How we choose supermarket locations

We draw on the Australian Bureau of Statistics Socio-Economic Indexes for Areas (SEIFA) product, which ranks areas in Australia according to relative socio-economic advantage and disadvantage, in order to choose supermarkets in locations ranking from low to very high in bigger capital cities.  

We also ensure a spread of locations across the country, and at each location we survey we make sure the supermarkets we are comparing are within 5km of each other to ensure that any variations in prices between stores are not due to them being in different locations.

All up our mystery shoppers visit 81 supermarkets – Coles, Woolworths, Aldi and IGA stores – in 27 locations across Australia.

How we compile our shopping list

In compiling our grocery list we include items regularly purchased by average Australians. The intent is to compare the prices of commonly bought items, rather than creating a basket that's representative of an average weekly shop. 

Basket items are also selected to give good coverage of grocery categories, including fresh food, beverages (tea), bread, cereal, frozen veg, pasta, chilled dairy and tinned foods.

Our mystery shoppers purchase the items on our list at each supermarket in their location, noting when items are on special and recording the regular price.

The fresh fruit and veg items are included because they are commonly purchased, but we keep the number of these items to a minimum because the quality and availability of fresh produce can vary widely across stores and geography, creating too many variables for a fair price comparison.

The CHOICE shopping list gives you a full list of the grocery items we price.

How we select brands and products

In order to make the most accurate comparisons, many of the products in our shop come from national brands (such as CSR, Sanitarium and Lipton), which are sold in most, if not all, major supermarket chains. Selection of the products for each basket item is based on wide availability, and the closest comparable items are selected when these are not available. 

We put a lot of due diligence into choosing our basket items to ensure we're making fair comparisons. Where possible we stick to more commoditised – or basic – items with limited differences across brands, to make sure we compare like with like. Canned tomatoes are chosen over ready-made tomato-based pasta sauce, for example, as pasta sauce recipes can vary significantly from brand to brand. 

We put a lot of due diligence into choosing our basket items to ensure we're making fair comparisons

We also spend a lot of time in stores and online to make sure the items we choose are comparable – that means they need to be the same size and similar in product quality, as well as appearance. 

Data collection and analysis

CHOICE engages with a qualified partner accredited with the Mystery Shopping Providers Association to undertake the fieldwork. Undercover shoppers visit the nominated supermarkets in a single week between Thursday and the following Tuesday to avoid the price changes that generally occur on a Wednesday. 

For each item, we provide shoppers with a photo and specify the quantity, weight or pack size to make sure they're collecting prices for the correct product. 

Shoppers are required to purchase the items in our basket so that we have receipts for each purchase, which we use to verify the recorded prices. 

When products are on special they photograph shelf labels showing the regular price. A price is deemed to be a special when we have evidence of a temporary price reduction. 

The data is collected via an online survey platform that requires shoppers to enter prices in a consistent format for each item before they can complete the shop. Every shopper's price list is validated for accuracy and completeness for quality assurance.

Other considerations when shopping for groceries

Supermarkets are an enormous source of research fodder, and the focus of this piece of research is on price. 

But we understand that many other factors are often considered when choosing where to shop or which products to buy, including convenience, nutrition, quality, supporting smaller and/or local producers and country of origin. And for some people, these other factors may be a higher priority than price.

Rest assured, our work on supermarkets isn't focused only on prices. Here's some of our other recent work on supermarket tactics and products. 

The CHOICE shopping list

We care about accuracy. See something that's not quite right in this article? Let us know or read more about fact-checking at CHOICE.

Stock images: Getty, unless otherwise stated.