SAN FRANCISCO: Discrepancies between Facebook's conversion tracking and advertisers' web analytics could mean that advertisers are missing out on some of their investment in mobile ad campaigns, according to a recent report.

For its Facebook Measurement Divide report, Rakuten Marketing Insights looked at the performance data of a selection of its clients and revealed that marketers who rely solely on third-party analytics are not realising all earned Facebook revenue.

It said these discrepancies mean some marketers are missing insight into 192% more attributable revenue from their mobile campaigns, and Rakuten described the mismatch as "not trivial".

For example, one of its clients included in the study saw a return of $1.9m from a Facebook campaign when the attributable return was in reality closer to $4.7m.

"Facebook conversion tracking is inconsistent with what advertisers see in their web analytics for many reasons," the report said.

"Although Facebook conversion tracking paints a more comprehensive picture of performance, there are technological challenges that prevent conversion tracking on Facebook from functioning correctly. This discrepancy means there are additional conversions happening that are simply not recorded anywhere."

The problem is minimal for desktop – where there is an average 3% attributable revenue discrepancy between Facebook conversion and web analytics – so the issue Rakuten identified mostly involves mobile campaigns.

Mobile is much more difficult to track and the report said some of the discrepancy can be attributed to certain mobile operating systems and internet browser combinations that block third-party cookies.

Another issue concerns Facebook's model of attribution, which captures all post-click conversions, whereas web analytics typically captures only last-click conversions.

Likewise, Facebook captures all post-impression conversions within 24 hours, but web analytics cannot capture these conversions from viewed inventory.

Tony Zito, CEO of Rakuten Marketing, said the findings showed that marketers need to be "diligent about gaining transparency into their performance measurement".

"Innovation is affecting consumer behaviour at a pace that does not allow for one-time attribution models that will accurately measure current and future marketing strategies," he said.

"Our focus is to arm marketers with actionable insights that empower them to capitalise in the rapidly evolving landscape in which they compete."

Data sourced from Rakuten Marketing; additional content by Warc staff