About our survey

Our shoppers bought from a list of 40 top-selling supermarket items. The list included bread (the supermarkets’ top-selling item by volume) as well as biscuits, milk and fizzy drinks – all among the top 10 sellers. Personal care and cleaning products were also on our list.

The survey didn’t include fresh meat, fish or produce because for a fair comparison we’d need to consider quality.

We’ve also excluded wine and beer, although beer was the top-selling category by value in supermarkets during 2010. Discounts on beer and wine are so huge that a supermarket with a listed beer on special would have an unfair advantage.

For most items we specified a brand and a pack size. But for 12 basic items we specified just the pack size – and asked our shoppers to buy the cheapest brand.

Buying the cheapest

Household budgets are stretched trying to keep up with the cost of living: between March 2010 and March 2011 grocery food prices rose 5.5 percent. So this year we’ve doubled the number of basic items on our list by adding frozen and canned foods and spreads to traditional basics such as bread, milk, sugar and butter.

To check the savings you can make we asked our shoppers in three cities to buy a two-litre bottle of branded milk (Anchor in Auckland and Wellington, Meadow Fresh in Christchurch) as well as the cheapest two-litre bottle they could find in each store. On average you could save more than a dollar on milk in Auckland and Wellington and around 70 cents in Christchurch by buying on price.

As well, our shoppers took advantage of multi-buy specials – for example, they’d buy two tins of cat food for $5 instead of a single tin for $3.19. We calculated the price of one item in the multi-buy and used this in our final total.