Field Data vs Lab Data: Which to Trust

Field Data vs Lab Data: Which to Trust

These two sit side by side in every report and confuse almost everyone. Field data is what real visitors actually experienced over the last 28 days. Lab data is one test from a controlled machine. Think of field data as customer reviews and lab data as a single taste test in the kitchen.

How to tell them apart and use each:
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1. In PageSpeed Insights, the top 'real users' block is field data.
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2. The lower block with a stopwatch icon is lab data.
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3. Use field data to decide IF you have a problem.
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4. Use lab data to debug WHY, since you can run it over and over.
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5. New or low-traffic pages show no field data — that's normal, lean on lab.

Field answers 'are users hurting?' Lab answers 'what's the cause?'

Try this: Open your report and label each block out loud: field or lab.