A shorter repeat checkout shows its value in how often customers come back, not in this week’s conversion rate
A faster checkout is usually judged on one number: the share of started checkouts that end in an order. For a returning customer that number says little, because the main effect of a shorter route lies elsewhere. What it can change is whether the next order happens sooner, contains more, and reaches into parts of the range the customer had not bought from before. None of that appears in a weekly conversion report, which is why one-click ordering is easy to underrate and easy to sell on the wrong promise.
A study by Murat Unal and Young-Hoon Park of Cornell University measured exactly that longer effect. Their paper, “Fewer Clicks, More Purchases”, appeared in Management Science in 2023. The data are older than the publication suggests: they cover 2016 to 2018 at one omnichannel retailer in Asia selling clothing, personal care products and shoes. Before January 2017, a shopper there filled a cart and then confirmed shipping and billing details as separate steps. From that month, customers could sign up for one-click buying, which reduced ordering to a single step. 977 customers did so between January and September 2017.
What fifteen months of shorter ordering added
The researchers did not simply compare these customers before and after. They matched each adopter with a customer who had behaved similarly beforehand but did not sign up, and followed both for 15 months. Measured that way, adopters spent about 28.5% more per month than the comparable customers, set against a pre-adoption baseline of roughly $20 a month. They placed 43% more orders and bought 36% more items, and the paper describes the effect as persistent. Cornell’s own report on the study adds that adopters visited the site 7% more often, viewed 9.3% more pages and stayed 7.8% longer per visit, and the paper shows purchases spreading over more product categories.
The gain was not borrowed from elsewhere. Purchases in the retailer’s physical stores showed no measurable change, so the online increase was not a move from one channel to the other. Returns did not change either. The authors used returns as a signal of impulse buying, and found nothing to suggest that one click led people to buy things they later sent back. That is the reassurance most teams want before shortening a route: more frequent, broader buying that customers keep.
The study has clear limits, which the authors name. It covers a single retailer in one sector, they cannot fully rule out bias from factors they could not observe, and they ask for replication at other firms. The percentages describe that setting. They are not a forecast for your shop.
The customers who asked for it first gained most
The study looked at which adopters responded most, and two differences were statistically significant. Customers who signed up early, in the first months after launch, showed a substantially larger effect than those who joined later. Older customers responded more than younger ones. The researchers also report that customers who had previously bought more often and for larger amounts saw a smaller increase, but those differences were not statistically significant. Cornell’s summary describes moderate, occasional buyers as gaining more than both the heaviest and the lightest spenders. Treat that as a direction worth testing, not a result.
The early-adopter finding is the most useful for design. Everyone in the study chose one-click buying, and those who chose it first got the most from it. A shortened route works for customers who want it and understand what it does. It should be offered and explained, not switched on silently. A one-step order needs a stored delivery address, a delivery choice and a payment method the customer agreed to keep, and the customer must be able to see and change each of them before the order goes through. A parcel sent to an old address costs more goodwill than the saved clicks earn.
In the Netherlands, shorten everything around the bank approval
Most one-click checkouts assume a stored card. Dutch shoppers mostly pay by bank: according to the Dutch Payments Association, iDEAL accounts for 71% of all online purchases. With iDEAL the shopper approves every payment with their bank, so the payment itself does not become a single click. The steps around it can shrink. iDEAL’s own fast options let a shopper save a preferred bank account, so they approve through a push notification instead of choosing a bank each time, and share delivery and payment details automatically during checkout.
Whether or not you use those options, the principle from the study carries over: remove the separate confirmations between the decision to buy and the approval. A returning customer can find their last address, delivery option and payment method already selected, with a single review screen before the bank. Offer it after an order that went well, say exactly what will be kept, and make it easy to switch off in the account.
Measure it against customers who did not opt in
Customers who choose a faster route are likely to be more engaged to begin with, so a plain before-and-after will flatter it. Do what the researchers did. Compare customers who use the shortened route with similar customers who do not, over at least a year, on orders per year, items per order, categories bought and return rate. Split the result by when customers signed up and by age group where you hold it, and check whether occasional buyers respond differently from regulars.
Start by counting the steps a returning customer goes through today, from cart to bank approval, on a phone. Then check what share of last year’s repeat customers ever saved their details. That share is the population your comparison will be built on.
Sources: news.cornell.edu, ecommons.cornell.edu, betaalvereniging.nl and ideal.nl
