Always On Special: 10 Weeks of NZ Supermarket Mailers

Every Monday I read the Woolworths and New World mailers and write down each lunchbox item on special, along with the regular price where the mailer prints one. That file now holds 10 unbroken weeks, 6 July to 7 September.

It answers a question a single week's mailer cannot: is the thing on special this week actually a bargain, or is it on special every week?

For three items, the answer is every week.

The 10-week record

"On special" counts a week where at least one product with that ingredient was discounted at either chain. "Discount measured" is the smaller number of those weeks where a regular price was printed next to the sale price, so I could work out how much came off. Where that number is under three I do not report a median at all — carrots were on special in nine weeks but priced in one, and a median of one reading is not a median.

Yoghurt, bread and cheese

Those three were discounted somewhere in all 10 weeks. Not most weeks. All of them.

That changes what the word means. If cheese has been on promotion every week since 6 July, the promotional price is closer to the real price than the shelf tag is, and "wait until it goes on special" stops being a strategy — it is a description of Tuesday. The shelf tag on those three is best read as the price you pay for not looking.

There is a second-order effect worth naming. Because these items are always discounted, they are also the items where a mailer looks most generous. A front page full of bread, cheese and yoghurt is a front page full of things that were going to be discounted anyway.

The discount moves even when the discounting does not

Yoghurt's best discount, week by week:

14% · 30% · 39% · 51% · 37% · 32% · 25% · 34% · 33% · 23%

Discounted in every one of those weeks, and priced in every one of them too, so this row is as solid as anything here gets. But the size ran from 14% to 51%, median 33%.

That is the useful shape. Whether yoghurt is discounted is not a question. How much is, and the difference between a 14% week and a 51% week is real money across a term. It is also completely invisible if all you look at is the word "special" on the shelf edge.

Bread does the same thing with gaps in it:

35% · 40% · — · 52% · 18% · — · 27% · 20% · 27% · 27%

The dashes are weeks where bread was on special but the mailer did not print a regular price to compare against, or weeks it did not appear. Either way I will not put a number there.

The two chains do not discount the same things

Cheese and yoghurt are near-constant at both chains — 8 and 9 weeks for cheese, 9 and 10 for yoghurt. Below those two the chains diverge, and the split matters if you only shop one of them.

Bread is a Woolworths habit — 8 weeks of 10 against 5. Carrots run the other way, 7 against 3. Neither is a big enough sample to be a law, and both chains are perfectly capable of changing habit next month, but it is the sort of thing worth knowing if you have already decided which supermarket you use and are choosing what to buy there rather than where to go.

What I would actually do with this

Stop treating the always-discounted items as opportunities. Bread, cheese and yoghurt do not need timing. Buy them when you shop. Waiting for cheese to come down is waiting for something that has not been at full price in over two months.

Do not confuse a big discount with a cheap lunch. The two do not track each other, and on this site's menus they barely overlap at all — that turned out to be a large enough problem to get its own article, because the planner had been getting it wrong.

Spend the attention on the rare ones instead. Of the 67 different items that turned up at all, 14 appeared in exactly one week. Those are the ones where a special genuinely is an event, and where buying two is worth it if the thing keeps.

I want to flag something about that second number, because it cuts the other way from everything else here. A "10 out of 10" claim gets stronger the patchier my collection is — if I missed items some weeks and yoghurt still showed up every week, that is more convincing, not less. The once-only count does not work like that. If my reading was thin in the early weeks, some of those 14 items were probably on special in weeks I did not catch. Treat it as a floor on how much variety there is, not a fact about the mailers.

Why there is no "specials are getting more common" section

I nearly wrote one. The count of promotions I recorded per week runs 29, 21, 36, 21, 33, 42, 54, 54, 56, 104 — from the twenties in July to past a hundred in September. That looks like a clear trend and would have been an easy paragraph.

It is not a trend. It is me. From September I started entering the mailer PDFs in full instead of picking items off the chains' websites, so I am recording roughly three times as much of the same reality. The supermarkets did not triple their specials; my notebook got bigger.

The same problem sank a second finding. Across those 10 weeks, 60% of New World's specials are member-only prices, which would be worth knowing. Split by week it goes 50%, 44%, 55%, 73%, 47%, 65%, 0%, 100%, 97%, 62%. A supermarket's membership policy does not flip between nothing and everything from one week to the next. I was labelling them inconsistently, and the total was hiding it.

Both are in this article as absences on purpose. If a number in a time series moves at exactly the point my method changed, the method is the more likely explanation, and splitting the total by interval is what shows it.

What I would not claim

This is two chains, not three. Pak'nSave is in the price index but not in this file — I read its mailer differently and do not have 10 clean weeks of it, so including it would mean padding.

"On special" here means on special in a mailer I read, which is a North Island mailer. Chains vary promotions by region and New World stores are individually owned, so your store may differ.

And the median discounts lean on weeks where a regular price was printed. New World frequently does not print one. Where that made a row too thin to trust, the table says so rather than guessing.

The full week-by-week file is what the planner reads when you tick "Plan around this week's specials", so you can check any of this against what it offers you.

Plan a week of lunches →