Beyond last-click: Relevance presents retail research at TikTok Day

At this year’s TikTok Day at Technopolis, Relevance took the stage to share research addressing this question.

A first-of-its-kind research initiative in Europe, the project reflects our commitment to innovation in measurement and to finding new ways to understand advertising effectiveness.
 

Τhe research analyzed nine Greek retail brands over an eight-week period, from March 4 to April 29, 2026. By combining GA4 reporting, TikTok Ads Manager insights and Conversion Lift Studies, we explored the relationship between attributed purchases and TikTok’s incremental contribution to sales.

Last-click attribution assigns credit to the final tracked click before a purchase. While useful for understanding the last step in a customer journey, it can overlook the contribution of advertising encountered earlier.

A consumer may discover a product through a TikTok ad and later complete a purchase through another channel. In a last-click report, TikTok may receive no credit for that sale.
 

Meanwhile, TikTok Ads Manager reported that 82.7% of TikTok-attributed purchases were view-through conversions, with shoppers taking an average of 5–8 days to convert. These findings point to customer journeys that extend beyond an immediate ad click and purchase.

For brands, this creates a challenge: assessing a platform solely through last-click reporting can lead to an incomplete understanding of its performance.

These metrics answer different questions: GA4 reports attributed purchases, while Conversion Lift Studies estimate the additional conversions caused by advertising. The contrast demonstrates why attribution alone cannot fully assess incremental business impact.

It compared each retailer’s Smart+ Adoption Share with a normalized Purchase Lift Index, which assessed purchase lift relative to the average lift across measured funnel events. Higher Smart+ adoption was associated with stronger relative purchase lift in the accounts analyzed.

This finding suggests that Smart+ Catalog Ads warrant further testing as part of a commerce-focused strategy. The relationship observed across retailers does not, by itself, establish that greater Smart+ adoption caused the stronger lift.
 

By incorporating incrementality testing into their measurement approach, advertisers can better understand which campaigns generate additional revenue and use that evidence to inform their strategy.

The research supports using each measurement tool for a distinct purpose: Conversion Lift Studies to evaluate incremental impact and inform investment decisions, GA4 to understand website performance and cross-channel journeys and TikTok Ads Manager to support campaign optimization.

For retailers, the next step depends on the findings. Strong incremental performance can support a case for scaling investment, while weaker results may point to the need to refine creative, product experience or campaign mix before increasing spend.