A retailer's TikTok gallery page reports its own lift

The test

TikTok's own case study on the athleisure retailer Gym King, run with agency partner Journey Further, describes a campaign the case study says launched in late August 2022. The creative approach combined In-Feed Ads with Collection Ads that opened into an in-app Instant Gallery Page, letting viewers browse products without leaving TikTok. TikTok's account emphasizes that Gym King diversified and refreshed its creative frequently, rotating seasonal assets from summer into autumn and winter content, including a Black Friday push. On targeting, the case study cites a Value-Based Optimization bidding strategy and lookalike audiences built from users who had added items to cart.

What the evidence says

The case study reports the campaign exceeded its video-view target by 292% and cut cost per view by 91% against Gym King's previous campaign, alongside a 25% increase in reach. A separate set of figures is framed as year-on-year for 2021: a 198% increase in purchases, a 759% increase in new followers, a 63% decrease in cost per acquisition, a 51% decrease in cost per page view and a 5.21% decrease in cost per mille. One set of numbers is tied to the campaign's own prior performance; the other is labelled year-on-year against 2021 — two different baselines within the same document, left unreconciled. All of these figures are TikTok's own reporting of a client campaign, not an outcome Gym King has separately disclosed in this record.

The sample and the variance

This is a single retailer's campaign across two named periods — a 2022 launch and a 2021 year-on-year comparison — so the case study spans more than one calendar year without a single continuous timeline. Percentage changes against "previous campaign" and against "2021" describe different comparisons, and neither baseline's absolute numbers are published, so a reader cannot verify a 292% or 759% change against a starting count. The case study sits on TikTok's own case-study hub, curated to show a working example of Collection Ads and gallery pages, not a controlled test against a matched retailer that skipped those formats.

What to try next

This is an editorial checklist, not a guarantee that a gallery-page format or lookalike-from-cart audience will reproduce these figures for another retailer. A commerce marketer can reasonably ask which baseline — the prior campaign or the prior year — any cited percentage refers to, request the absolute reach and spend behind a cost-per-acquisition change, and test a Collection Ads gallery against a plain in-feed format before assuming the gallery format alone drove the reported lift.

• Which baseline does each percentage in the case study refer to: the prior campaign, or the 2021 comparison?
• What portion of the reported purchase increase is attributable to the seasonal Black Friday period specifically?
• Would a lookalike audience built from cart-adders outperform a standard interest-based audience outside this retailer's category?

Gym King's case study documents a specific format and targeting combination TikTok is promoting, with results TikTok itself selected and reported; it is evidence of what happened for one retailer across two comparison points, not a benchmark another advertiser should expect to clear.