Challenges with Google Analytics 4’s Attribution Model

Recently, a white paper by the CPA, a respected French digital marketing trade association, shed light on the challenges faced by affiliate marketers and beyond due to Google Analytics 4 (GA4).

GA4 heralded a new era when it made data-driven attribution (DDA) its default model in April 2023, departing from last-click attribution which had been a stalwart since the early days of the internet. While last-click attribution allocates full credit for a conversion to the final touchpoint in a customer’s journey, DDA aims to distribute credit more equitably across all interacting touchpoints. It does this by assessing how the presence of a given traffic source in the user journey affects conversion probability. This sounds great on paper, but the white paper published by CPA paints a picture that’s far from rosy.

Insights from the CPA white paper

At Kelkoo we’ve long suspected that our traffic was being under-attributed by the DDA model. The white paper supports our suspicions with others in the affiliate space observing discrepancies between their conversion data and GA4’s of anywhere up to 80%. This is a marked increase from the 10-25% seen with GA3’s Universal Analytics (UA) and has been making waves in the industry ever since DDA became the default attribution model in GA4 in April 2023. The white paper underscores several critical issues with the DDA model in the context of affiliate marketing. Of particular concern is the potential bias towards Google’s own traffic. According to the paper, GA4 may prioritize interactions originating from Google channels, such as Google Search or YouTube ads. This assertion isn’t entirely surprising, given Google’s history of self-preferencing, evidenced by adjustments to search-results pages following regulatory scrutiny by the European Commission.

“Beyond the minimum threshold of 300 conversions required for a channel to become visible in GA4’s DDA model, interactions with Google channels also benefit from increased valuation in this model.”

– GA4 and Affiliation white paper (translated from the original French)

Moreover, the findings of the white paper beg the question as to whether inherent conflicts of interest are unavoidable, particularly where Google is concerned and who famously dropped their “Don’t be evil” motto, replacing it with the far less catchy “Do the right thing” in October 2015. Its actions however, suggest the mottos are nothing more than a cosmetic branding exercise. Can a company responsible for both tracking (via GA4) and delivering conversions (through Google Ads) remain impartial when assessing the value of various traffic sources? It’s hard to imagine the answer to that being a resounding “yes” given the company’s track record.

“Google pays particular attention to advertising data from its own channels and network, leading to a more consistent and preferential measurement of interactions with the Google ecosystem compared to other non-Google acquisition channels.”

– GA4 and Affiliation white paper (translated from the original French)

Ultimately, the white paper asserts that the manner in which GA4 tracks Google’s own traffic may lead to an imbalance in value assignment, potentially skewing results in favour of Google Ads over affiliate marketing efforts. This paints a stark picture for fairness and proper competition within the industry.

There is no doubt that as more and more traffic partners battle for attribution, and users regularly interact with ads, videos, search results and more before finally purchasing, that the last-click model becomes increasingly strained. Google’s attempt to put a nail in the last-click coffin is admirable, but under the guiding light of attribution equity have we simply landed somewhere far more troubling?

Exploring solutions

In addressing these challenges, the white paper, echoing industry sentiments, advocates for a return to the last-click attribution model utilised in previous iterations of Google Analytics. While last-click attribution may oversimplify the intricacies of the customer journey, it offers a transparent and comprehensible method of credit assignment and acknowledges that for the most part recency trumps all.

“Although GA4 is a powerful tool for tracking overall website performance, it’s advisable to regularly consult the data provided by affiliate platforms for accurate information on conversions and revenues generated by your affiliate partners.”

– GA4 and Affiliation white paper (translated from the original French)

However, a complete reversion to last-click may not present the optimal solution. The industry may benefit from exploring alternative attribution models that provide a more balanced perspective than DDA while acknowledging the significance of multiple touchpoints. Beyond some account and parameter housekeeping, the paper suggests that GA4’s Model Comparison Report is a great way to assess how DDA and last-click models compare. At Kelkoo, we recommend using this report to help you assess the performance of all your channels from multiple perspectives.

Collaboration, and impartiality for the future

Moving forward requires a multifaceted approach.

• Collaboration between Google and marketing platforms is imperative to establishing a fair and accurate measurement system – affiliates play a pivotal role in the conversion funnel.

• Affiliate marketers need to remain cognizant of GA4’s limitations and potential biases. Relying on last-click data from their respective platforms offers a valuable benchmark for comparison.

• Prioritising metrics beyond conversions, such as clicks and impressions can provide a more holistic view of campaign performance.

GA4 and the future of affiliate marketing

The ubiquity of DDA as the default model poses a formidable challenge to the affiliate marketing landscape. Marketers confront the risk of undervaluing vital acquisition channels. While the white paper does make recommendations, such as reverting to last-click attribution or exploring alternative models, industry-wide collaboration with Google is imperative to ensure a fair and precise measurement system. The question is, will Google recognise or even acknowledge these findings? Seems unlikely!  

“If advertisers base their spending entirely on the best-performing channels indicated by GA4, this could lead them to abandon all other channels, skewing the data in favour of Google-owned channels.”

– GA4 and Affiliation white paper (translated from the original French)

It’s up to those in the affiliate and performance marketing industry to educate each other and advertisers on DDA’s limitations. Only by advocating for transparency and proper equity can we expect to see fair and beneficial change. Until then, it’s clear that despite best efforts, last-click is still a very reliable indicator of performance when it comes to the majority of bought traffic. So, if you’re a GA4 user, your should take advantage of the different models available to view in the Model Comparison Report to get a more complete picture of conversions across your site.