Field data (also called Real User Monitoring or RUM data) represents performance metrics from actual visitors to your website. It captures real-world conditions including device variety, network conditions, and geographic distribution.
Field data vs lab data
| Aspect | Field Data | Lab Data | |--------|------------|----------| | Source | Real users | Simulated | | Conditions | Variable | Controlled | | Coverage | Pages visited | Tested pages | | Timing | Continuous | On-demand | | Devices | All user devices | Emulated |
Sources of field data
- CrUX: Chrome User Experience Report
- RUM tools: VitalSentinel, SpeedCurve, etc.
- Web analytics: Some metrics from GA4
Why field data matters
- Shows actual user experience
- Captures edge cases and real-world issues
- Used by Google for ranking signals
- More representative than lab tests
Field data limitations
- Requires traffic to collect
- Takes time to accumulate
- May not cover all pages
- Subject to sampling in CrUX
Related Terms
Chrome User Experience Report (CrUX)
A public dataset of real user experience data from millions of websites, collected from Chrome users who have opted in to usage statistic reporting.
Core Web Vitals
A set of three metrics defined by Google that measure the loading performance, interactivity, and visual stability of a web page.
Lab Data
Performance metrics collected in controlled testing environments using tools like Lighthouse, as opposed to field data from real users.
Real User Monitoring (RUM)
A type of performance monitoring that captures and analyzes data from actual user sessions visiting a website.