Glossary · Measurement and evidence
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
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. Field data, gathered from real visitors, is what the ranking systems use.
What lab data can and cannot support
| It can support | It cannot support |
|---|---|
| Performance measured by loading a page once in a controlled environment, as Lighthouse does. Field data, gathered from real visitors, is what the ranking systems use. | 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. |
Terms this definition uses
Definitions that name lab data
Related terms in Measurement and evidence
The vocabulary for saying how strongly something is known.
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 · 668 terms across 19 areas.