B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Recent
87%
87% -- expected impact drop per test for CRO teams running 30+ tests per engineer per year (2025)
Expected impact per test drops by 87% when running beyond 30 tests per engineer per year.
Attribution:
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Lighthouse Research Team
Last verified:
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Source verified
Evidence graded
Value
87%
Unit
Percentage
Data Vintage
2025
Entity
Sample Size
127,000
Evidence Quality
B
Strong, reliable evidence
Sourced from a well-regarded research firm or industry leader with transparent methodology and a reasonably large sample.
Single source - not yet corroborated
Score breakdown
Extraction
75
Source Trust
60
Citation Chain
20
Independence
30
Methodology
45
Freshness
95
Source
Optimizely
Primary
Tier B
https://kirro.io/cro-process ↗
Source Article
CRO Process: 5 Steps to Better Conversions
The CRO process is a repeating cycle: research what’s broken, form a guess about how to fix it, test that guess, and learn from the result. Then do it again. It’s how you stop guessing about your website and start knowing what works.
Most companies skip this entirely. An Econsultancy study of 450+ b…
Original Research
Optimizely
· Original study ↗
Methodology
Optimizely analysis of 127,000 experiments, cited by kirro.io
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
CRO teams running 30+ tests per engineer per year: 87% expected impact drop per test. Source: Optimizely (2025). Via Lighthouse Intelligence -- https://lighthousedata.io/data/optimizely-impact-drop-30-tests
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<blockquote cite="https://lighthousedata.io/data/optimizely-impact-drop-30-tests" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>87%</strong> -- expected impact drop per test for CRO teams running 30+ tests per engineer per year<br><small>Source: Optimizely (2025) · <a href="https://lighthousedata.io/data/optimizely-impact-drop-30-tests" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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