How to Read Retail Media Co-op Ad Reports — Seeing Purchases, Not Just Clicks, Without Your Own Store

Ad reports usually break right after the click. This month’s clicks and visits are in the report, and sales on Olive Young, Korea’s largest health and beauty retailer, went up in the same period, but nothing connects the two. For brands that sell mostly through third-party retailers rather than their own store, that gap is even wider. Co-op advertising, a form of retail media, is designed to close it. Based on what Korean ad-tech firm Buzzvil shared on Mobiinside, here’s what co-op ads connect and how to read the reports.

What co-op ads bring together

Co-op ads only work when three parties contribute:

• The retailer supplies data on what users searched, added to cart and bought, plus a product catalog with names, prices, images and coupons.
• The publisher network supplies inventory where people already spend time. In Buzzvil’s case, that’s about 500 premium Korean media properties reaching 24 million users a month.
• The brand decides which products to open, when, in what creative format and with what budget.

On their own, brands can’t link third-party purchases to ad exposure, retailers can’t see ad touchpoints outside their app, and publishers can’t see purchases after a click. Co-op ads join the three so you can follow ad response through to cart and purchase.

The five-stage report

Co-op ad reports break the user journey into impressions, clicks, engagement, add-to-cart and purchase, at campaign, ad set and creative level.

Engagement between click and cart

A click only tells you someone tapped. It can’t separate accidental taps from people who left immediately, so when CTR is high but sales are low, it’s hard to tell whether creative or targeting is the problem. The engagement stage captures actions after the click, such as reading reviews, answering a quiz, watching a short video to the end or claiming a coupon. If a click means “tapped,” engagement means “looked closely.”

It isn’t perfect. With weak identity signals or thin in-app event data, the connection loosens. Better measurement doesn’t mean zero error; it means you can see where the link holds and where uncertainty begins.

Check the campaign goal before ROAS

Judging by ROAS alone misreads half your campaigns, because they serve two goals:

• Purchase-focused campaigns convert people likely to buy now. ROAS and add-to-cart conversion are the honest metrics.
• Audience-building campaigns create first touchpoints with people who don’t know the brand. Judge them by new reach and how those users respond in later campaigns, not immediate ROAS.

Three lessons from CLIO

1. Focus on the stages ads can move

In Korean cosmetics brand CLIO’s March and June sales, ROAS fell from 1,500% to around 960%, yet the share of carted items that reached checkout was the same both times: three in ten. Checkout conversion depends more on product strength, price and promotion than on ads. The ad’s job is producing carts cheaply and at volume.

2. ROAS is an outcome, not a cause

June’s budget and clicks were similar to March, but impressions nearly doubled. ROAS alone says efficiency dropped; adding impressions shows the same budget bought far more reach.

3. Judge creative by cost per stage, not revenue

Measured by cost per add-to-cart, the recommendation-style banner that led March revenue cost over 700 won per cart, while an OX quiz format expected to contribute little cost in the 400-won range. In June, the quiz format ranked first. Cutting by revenue rank would have lost it.

Takeaways

Brands that rely on retailer sales should ask “where did people drop off?” before “did it work?” when reading retail media reports, and decide creative swaps by mid-funnel unit costs like cost per cart. For more on linking ads to purchases, see How Revlon Used Amazon Interactive Video Ads to Get a 9.8x Higher CTR — Dynamic TV Creative Bridges TV and Purchase and Amazon Ads Agent Unifies DSP and Ads Console — Full-Funnel Campaigns, DVA+ and Conversational AI.