Behind the Cookie Banner: Using GA4 Consent Data to Understand Trust

To address these challenges (and help you), we developed a User Consent Dashboard. It's helped our clients do something they couldn't do before: compare behaviour between users who consent to cookies and those who don't.

Here's what that unlocks.

Most consent platforms stop at "how many users said yes."

That's an important metric, but it doesn't let you answer some critical questions, like:

• What happens after they say yes or no?
• Do these groups behave differently on your site?
• Do some traffic sources earn more trust (and opt-ins) than others?

Your CMP won't tell you that. But GA4 can (when set up correctly).

We designed our dashboard to break down user behaviour based on their cookie consent status. It surfaces deeper insights and gives the ability to present them in a way that's easy to understand. Specifically, we break out:

• Analytics Cookies: Typically relating to Google Analytics permissions
• Performance/Targeting Cookies: Typically relating to Paid Advertising platform permission

Every GA4 event provides data on the users' opted-in status for Analytics and/or Ads cookies. At this event level, we can derive numerous meaningful insights with compelling visualisations created alongside our clients.

What's actually in the dashboard:

• Every GA4 event, along with its opted-in and opted-out status.
• GA4 events (broken down by key custom dimensions).
• Opt-in rates by device, browser, location, and other factors.
• Campaign information (inferred from the parameters in the query string).
• Opt-in rates for Performance/Targeting Cookies (showing how much of your data you can use within Paid Marketing Platforms).

1. Understand Where You're Earning Trust

Whether by region or traffic source, or by examining opt-in rates over time, we aim to identify patterns in who agrees to cookies. For example:

• Do you need to optimise your cookie banner for each world region with different privacy laws?
• Has your brand campaign increased trust (shown by higher opt-in rates)?
• Are some platforms under or over-reporting based on consent rates?
  • If so, how should budgets shift?

2. Track the Impact of Cookie Banner Changes

Monitor the opt-in and opt-out rates before and after a Cookie Banner update. Know what impact that has had on user engagement or conversions. Have you implemented any changes that have negatively impacted your consent rates and data quality?

3. Drive Change

Cookie banner optimisation is mega important. We can't overstate the direct impact on GA4 and Paid Advertising Platforms. You're missing out on data if you're not optimising your cookie banner for better consent rates, all while complying with GDPR and other privacy regulations.

To drive change, you need to make a case for your stakeholders. When you have no data on the impact on conversions, that is even harder. When you have a dashboard showing that you're only sharing 50% of your conversions for Facebook to use when optimising campaigns, you're missing out on some easy ROAS uplift. You have much more power to drive change.

We've run this dashboard across multiple clients, and here's what keeps showing up:

• Users who convert are much more likely to opt in: It makes sense. Users who trust you are more likely to make a purchase and provide consent. Now, the data proves it.
• There are considerable differences in opt-in rates across channels: Email often performs well. Snapchat? Not so much. These behaviours reflect user intent, trust, or accidental clicks that bounce before giving consent. Each is an indication of whether your site is receiving good-quality traffic.
• Different countries respond differently to cookie banners: The USA sees much higher opt-in rates than Japan. That tells us something about markets, as well as specific trust and privacy perceptions.
• Beware of layout shifts on mobile: One client's dashboard highlighted a significantly higher opt-out rate for mobile. Upon prompting an investigation, we discovered that the 'Accept All' button was positioned below the fold, whereas 'Reject All' was above, resulting in a significantly higher opt-out rate due to poor design.

To unlock this kind of insight, you need three key components:

1. Advanced Consent Mode

Consent Mode is nothing new. Google enforced consent mode in March 2024. What does Consent Mode do? It informs Google of the current consent status for every user, which in turn affects how Google processes data.

But there are two types:

• Basic Consent Mode: Blocks data collection entirely for users who opt out of tracking.
• Advanced Consent Mode: Sends anonymised, non-identifiable data when consent is denied, letting you compare behaviours at a macro level.

To compare opt-in versus opt-out behaviour, you need Advanced Consent Mode.

2. BigQuery Connected to GA4

Where Advanced Consent Mode enables data collection, it's BigQuery that unlocks it. We already recommend connecting every GA4 property to BigQuery. Here's why?

• Full data ownership
• Control and transparency
• Access to raw, unsampled data
• The ability to run advanced analysis (like this dashboard)

However, this is a required step for the User Consent Dashboard, as only the RAW data gives access to GA4 events for users who have denied consent.

3. The Fresh Egg GA4 Mastertable

The GA4 export to BigQuery is powerful, but it's raw and messy.

We've built a structured, scalable reporting table (the Fresh Egg Mastertable) that turns GA4 BigQuery chaos into something usable. It's consistent, robust, and fast to deploy. We can also layer in our own 'power-ups' later for advanced insights. The User Consent Dashboard is just the beginning.

From there, it's a short step to visualising the data in Looker Studio, tailored to the metrics that matter.