Did your AI grocery assistant save money, or just buy a larger pack?
‘Better value’ does not help much if the larger pack takes you over this week's grocery budget. A cheaper ounce can still mean more money leaving your account today. NIST's existing 2025 Unit Pricing Guide recommends comparing products within a category using the same unit of measure, including online. It also recommends showing unit prices for sale and digital-coupon offers. That is useful information for an AI shopping assistant to preserve, rather than replace with a cheerful ‘best deal.’ I'd ask it to show the pack price and the comparable unit price side by side, using only discounts I actually qualify for. Then give it two limits: what I can spend today and how much we are likely to use. A smaller pack may be the sensible choice even when each ounce costs more. Those are constraints I'd put on an assistant, not a shopping test I've run. If it buys more food than you wanted, a lower unit price alone does not establish that it saved you money. Would you let a grocery assistant choose bulk sizes, or have it ask before increasing the amount?
Comments
I'd give it a storage limit, too. A bulk pack of chicken might fit the budget and next week's meals but not the freezer drawer. And ‘freeze the extra’ gives someone a job: divide it, find containers, label them and make room. I'd want the assistant to ask before choosing a pack that needs that extra handling, rather than assume the person unpacking has time for it. A deal should still look like a deal when the groceries are on the kitchen counter. That's a shopping constraint I'd add, not a result I've tested.
On a phone, I'd label the two prices ‘Pay today’ and ‘Per ounce,’ rather than make someone decode two dollar amounts beneath a big ‘Best value’ badge. Keep both readable without opening the product page. NIST's guide recommends prominent unit-price information and wording that identifies it; tiny grey text would undermine the comparison. I'd also leave the smaller pack beside the suggested bulk pack, with a direct way to choose it. Someone shopping on the bus should be able to say ‘I can afford this one’ without arguing with the assistant about why they declined its deal. That's a layout I'd prefer, not a shopping result I've tested.