Google Analytics 4 (GA4) has been evolving rapidly, but one hot topic in 2025 is data sampling. Many marketers and analysts are noticing that GA4 reports now apply sampling more aggressively than before, which can lead to inaccurate insights. This change is pushing professionals to rely more heavily on BigQuery for precise, unsampled data.
In this post, we’ll explore why GA4 sampling matters, how BigQuery solves the problem, and best practices to ensure accurate reporting.
What’s Happening With GA4 Sampling
Historically, GA4 applied sampling only to exploration reports. However, as of late 2023, sampling now affects all reports, including:
- The GA4 user interface
- GA4 API queries
- Looker Studio GA4 connectors
Sampling typically occurs if your dataset exceeds 10 million events or includes high-cardinality dimensions, such as user IDs. The result? Approximated metrics instead of exact figures — not ideal if your decisions rely on precise numbers.
Why BigQuery is the Go-To Solution
Integrating GA4 with BigQuery allows you to export raw, unsampled event data, giving you full control over your analysis. Here’s why it’s essential:
- Accurate insights: No approximations, no guesswork.
- Complex queries: Join, filter, and aggregate your GA4 data exactly how you want.
- Historical analysis: Access long-term trends and patterns without sampling distortion.
Some users have reported challenges, such as GA4 exports stopping after linking additional services like DreamData. Monitoring these integrations is crucial to maintain a smooth data flow.
Best Practices for GA4 + BigQuery
- Connect GA4 to BigQuery: This is the most reliable way to bypass sampling and access raw event data.
- Optimize GA4 reports: Minimize high-cardinality dimensions and shorten date ranges in reports to reduce sampling triggers.
- Monitor exports: Regularly check your BigQuery dataset to ensure data is exporting correctly, especially after adding new services.
Conclusion
With GA4’s sampling affecting even standard reports, relying solely on the GA4 interface or API may no longer be sufficient for precise analytics. BigQuery integration ensures you have full, unsampled data, empowering you to make confident, data-driven decisions.
For businesses handling high-traffic websites or complex data, GA4 + BigQuery isn’t just a nice-to-have — it’s a must.
Pro Tip
If you’re still relying only on GA4 reports, now’s the time to connect to BigQuery and take control of your analytics. Start your integration today and avoid costly sampling surprises.
Check out my step-by-step GA4 to BigQuery linkage guidance here: How to set up BigQuery linkage in your Google Analytics 4 property