Lab data is performance data collected from controlled test environments. Tools like Lighthouse run tests with predefined conditions, providing consistent, reproducible results.
Characteristics of lab data
- Controlled conditions: Same device, network, location
- Reproducible: Tests can be repeated consistently
- Immediate: No need to wait for user traffic
- Detailed: Can capture every metric and timing
Lab data tools
- Lighthouse
- WebPageTest
- Chrome DevTools
- Synthetic monitoring services
Lab data metrics
Common lab metrics include:
- FCP (First Contentful Paint)
- LCP (Largest Contentful Paint)
- Speed Index
- TBT (Total Blocking Time)
- CLS (Cumulative Layout Shift)
When to use lab data
- Debugging specific issues
- Testing before deployment
- Comparing code changes
- Establishing baselines
Lab data limitations
- Doesn't reflect real-world variety
- May miss issues in specific conditions
- Not used by Google for ranking
- Can differ significantly from field data
Related Terms
Field Data
Performance metrics collected from real users in production environments, as opposed to lab data collected in controlled testing conditions.
Lighthouse
An open-source automated tool by Google for auditing the quality of web pages, measuring performance, accessibility, SEO, and more.
PageSpeed Insights
A Google tool that analyzes web page content and provides suggestions to make pages faster, combining both lab and field data.
Synthetic Monitoring
A type of performance monitoring that uses automated scripts to simulate user interactions and measure performance in controlled conditions.