lab data
Performance measured by loading a page once in a controlled environment, as Lighthouse does. It is repeatable in setup and not in result: the same page varies by tens of percent run to run, so one lab run cannot support a finding.
What lab data means
Field data, gathered from real visitors, is what the ranking systems use.
Where lab data comes up on this site
- Core Web Vitals field data for sites CrUX does not coverThis guide explains why field data is missing, why lab data cannot fill the gap, and how to collect field data of your own that is honest about its sample size.
- PageSpeed Insights and Lighthouse vs an AI crawler auditLab data and field data are different measurements PageSpeed Insights shows two kinds of number on one screen, and they answer different questions.
Terms this definition uses
Definitions that name lab data
Related terms in Measurement and evidence
The vocabulary for saying how strongly something is known.
read equivalence · content-change clock · self-claim ledger · agent task canary · revocation delta · signed verdict · hash-prefix lookup · k-anonymity · publication floor · data snapshot · evidence level · false positive · denominator note · percentile rank · population baseline · cohort asymmetry · self-audit invariant · unscored measurement · dated series · change receipt · regression · finding age · graded through a wall · self-audit · placeholder in record · fetcher disagreement · own-host loop · score version · row review · double-counted defect · cosmetic row · gated row · log file analysis · AI referral attribution · finding fingerprint · finding state · headroom · fix list · render gap · Lighthouse · RUM · LCP · CLS · INP · topicality · intent coverage · canary · citation rate · presence rate · answer stability
Questions about lab data
What is lab data?
Performance measured by loading a page once in a controlled environment, as Lighthouse does. It is repeatable in setup and not in result: the same page varies by tens of percent run to run, so one lab run cannot support a finding.
What does lab data not show or guarantee?
It is repeatable in setup and not in result: the same page varies by tens of percent run to run, so one lab run cannot support a finding.
Which area of the glossary does lab data belong to?
Measurement and evidence: The vocabulary for saying how strongly something is known.
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See it in the full glossary · 731 terms across 19 areas.