Field data vs lab data: which one decides?

Field data vs lab data: which one decides?

Lab data comes from a single test on a borrowed machine. Field data is real visits from real people over the last 28 days. Think of lab data like rehearsing a song alone, and field data like the actual concert.

When they disagree, field wins for ranking. Lab is only for debugging.

How to tell which you're looking at:
— In PageSpeed Insights (PSI — a free Google tool), the top section labeled 'Discover what your real users are experiencing' is field. That's CrUX (Chrome User Experience Report).
— The colorful 'Diagnose performance issues' section below is lab.

Try this: open PSI for your page and read only the top section first. If it has no data, you don't have enough traffic yet, so trust the lab section for now. This one's easier than it sounds.