Analytics tools were built on the idea that once someone visits your site, you can see what they do. No more.
With cookie consent platforms (CMPs) now the norm, a growing percentage of visitors are choosing to reject non-essential cookies – and that includes analytics. For businesses, this means Google Analytics (and similar tools) no longer reflect the full picture of how people interact with your site.
Consent is the law
In the UK, cookie consent isn’t a nice-to-have, it’s law. Under PECR and the UK GDPR, non-essential cookies (analytics, marketing, remarketing) can only be dropped with active, informed consent.
That means:
- Visitors must be told clearly what cookies do and why.
- Accepting or rejecting must be equally easy.
- Consent has to be freely given, specific, and unambiguous.
Essential cookies – things like shopping cart sessions, secure logins or payment processing are exempt. But the tools most marketers rely on, from Google Analytics to Facebook Pixel, are not.
What the numbers say
Recent UK studies show that when a “Reject All” or equivalent opt-out option is clearly visible, 15-30% of visitors choose to decline non-essential cookies. In cases where the default is set to decline, yet the design nudges towards acceptance, that percentage can shift – but you’re still losing a chunk of visitor data.
Other research puts the global acceptance rate for consent banners at around 30–40%, with wide variation depending on sector, country and how banners are implemented. In some Nordic countries, acceptance can reach 75–80%; in other markets it’s much lower.
The bottom line: relying solely on Analytics means basing decisions on an incomplete dataset.
The Google factor
Google has also raised the stakes. From January 2024, advertisers in the UK and EEA running personalised ads are required to use a CMP certified by Google and integrated with the IAB’s Transparency and Consent Framework (TCF).
For our clients, this has meant that running Google Ads campaigns effectively “forces” consent management onto the roadmap. Without it, ads don’t run – simple as that.
What this means for your data
If 20-30% of your visitors reject consent, that’s 20–30% of user journeys invisible in Analytics. Page views, bounce rates, funnel drop-offs – all those metrics only represent consenting users.
That introduces consent bias: the risk that the data you’re using to make marketing and UX decisions isn’t fully representative of your audience.
What you can do
- Audit your CMP setup – Make sure it’s compliant and recording consent signals properly.
- Leverage Consent Mode – Google’s Consent Mode can model behaviour for non-consenting users, helping fill some of the gaps.
- Use privacy-first analytics – Tools that don’t rely on personal data can provide cookieless insights alongside GA.
- Track trends, not absolutes – Recognise that Analytics now tells you “a story,” not “the whole story.” Focus on relative shifts and patterns, rather than absolute numbers.
Final thought
Google Analytics is still powerful, but it’s no longer the single source of truth. With a meaningful percentage of visitors declining cookies, your data now represents only part of the audience.
Acknowledging that gap and planning for it in your strategy means better decisions, stronger campaigns and a more realistic view of how people really use your site.