How Google Consent Mode bridges the gap between effective marketing and data privacy

Maria Thorpe, Head of Data Science,

The ‘privacy vs effective marketing conundrum’

Customer data is essential to effective digital marketing, but so is customer consent to personal data collection - both within GDPR and to building brand trust. These can often seem like competing priorities, where the more privacy-focused your business is, the less data you might have available to make marketing decisions. This is where Google Consent Mode excels - by combining the protection of users’ data with marketing’s need for information on customer behaviour.

What is Google Consent Mode?

Consent Mode dynamically changes the behaviour of tracking tags depending on the user’s consent choices. For users who consent, tracking operates as usual, but when website users do not consent to tracking, instead of storing cookies, tags send cookieless pings to Google. These pings might occur when a conversion has occurred, when a page is loaded, when events are logged or to communicate consent status. The pings communicate functional information (such as a timestamp) and non-identifying information (such as whether an ad-click previously featured in the user’s journey).

What happens without Google Consent mode?

Without Consent Mode, when you implement a consent banner for your website or app you lose data for users who do not consent. You might see this in your analytics data through inexplicably decreasing user numbers, or unexplained changes to the performance of different marketing channels. 

The problem with making marketing decisions on this observed data alone is that it’s likely biased. YouGov found that there were substantial differences based on age and location in the likelihood of users accepting all cookies, whilst Google suggests that consented users are between two to five times more likely to convert than unconsented users. This bias might manifest in a misunderstanding of customer characteristics or under attribution of paid media spend. Marketing decisions based on that biased data might end up shrinking rather than growing the business.

What’s the effect of Google Consent Mode?

In Universal Analytics these cookieless pings enable you to see the total traffic across your pages, and understand the impact Ads have in driving that traffic. However you might still be missing some information which may be unobservable without cookies, such as how many new users you have or what the user journey is to conversion.

In GA4 (Google Analytics 4) however, Consent Mode also interacts with machine learning features such as behavioural and conversion modelling. This estimates the behaviour of users who decline analytics cookies based on the behaviour of similar users who accepted them. It similarly looks to estimate where unattributed conversions are likely to have originated based on fully observed conversions.  

Google estimates that conversion modelling through Consent Mode recovers on average 70% of ad-click-to-conversion journeys otherwise lost through user consent choices. This gives a much more accurate picture of your website or app users - meaning you can make marketing decisions based on the best data available. 

Whilst you can’t directly retarget users who do not accept cookies, Google Ads can make use of the modelled conversions generated from Consent Mode. These modelled conversions are integrated directly into Google Ads campaign reports and Google’s bidding tools so that campaigns are optimised based on as full a view of users as possible. 

How do I use Google Consent Mode?

Firstly you’ll need a consent banner or widget. Google Consent Mode doesn’t replace these, but rather interacts with them. You could install these through a consent management platform (CMP), like OneTrust or Cookiebot, or a custom implementation for obtaining consent. Google provides a list of those CMPs which integrate with Consent Mode in its documentation.

Some Google products (Analytics, Floodlight, Conversion Linker and most of Google Ads) have built-in support for Consent Mode, but you can also add consent checks to tags through Google Tag Manager.  

Is it really GDPR compliant?

Paired with a GDPR-compliant CMP, Consent Mode only captures anonymised data for non-consenting users. This aims to balance the business’ legitimate interest in capturing some marketing data with the individual’s privacy rights. Get legal advice if you have any concerns regarding your privacy compliance.

The default set-up of Universal Analytics has come under fire for violating GDPR guidelines in Austria, France, Italy and Denmark. Implementing Consent Mode on its own does not change these rulings. That’s because these rulings relate to how Google Analytics processes data about all users, not just those who don’t consent to cookies (and rests on handling of IP addresses by Google in the US prior to anonymisation). According to some data protection authorities, server-side set-up of Google Analytics, which gives full control over exactly what data you permit Google to access about your website users, can be fully GDPR compliant.   

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These statements do not constitute legal advice. If you have any legal questions, you should consult a specialist lawyer.

Headshot of Maria Thorpe, with the 26 logo in the background.

Maria Thorpe, Head of Data Science

With a background in big data and implementing data science techniques across a range of industries, Maria now leads our Data Science team, harnessing those skills she's learned to supercharge marketing performance. 

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