The CRO Power Law: Why 80% of Wins Come From 20% of Tests
Article written by
Stuart Brameld
What Is the CRO Power Law?
The CRO power law is a variation of the Pareto Principle (also known as the 80/20 rule) applied specifically to conversion rate optimisation (CRO). It states that roughly 80% of your CRO wins come from just 20% of your tests. In other words, most experiments you run will have minimal impact, while a small number will deliver significant results.
This concept was popularised by Conversion Rate Experts, who analysed hundreds of CRO experiments across multiple industries. Their research consistently showed that a small fraction of tests accounted for the majority of measurable improvements.
You can read more about their findings in these articles:
Why the CRO Power Law Matters for Growth Marketers
Understanding the CRO power law helps growth marketers prioritise their efforts effectively. Rather than spreading resources thinly across numerous low-impact tests, marketers can focus on identifying and executing high-potential experiments.
By recognising that most tests will yield limited results, teams can:
Prioritise experiments based on potential impact and ease of implementation.
Increase experiment velocity to quickly identify high-impact tests.
Allocate resources more efficiently, maximising return on investment (ROI).
Build a culture of learning and iteration, rather than expecting every test to succeed.
Visualising the CRO Power Law
The following image from Conversion Rate Experts clearly illustrates the CRO power law in action:
Image source: Conversion Rate Experts
The graph demonstrates how a small number of tests (on the left side) deliver disproportionately large improvements, while the majority of tests (on the right side) have minimal or no impact.
How to Apply the CRO Power Law to Your Growth Marketing Strategy
To leverage the CRO power law effectively, growth marketers should adopt a structured approach to experimentation:
Hypothesis-driven testing: Clearly define hypotheses based on data and user insights, ensuring each test has a strong rationale.
Prioritisation frameworks: Use frameworks such as ICE (Impact, Confidence, Ease) or PIE (Potential, Importance, Ease) to prioritise tests objectively.
Rapid experimentation: Increase your experiment velocity to quickly identify high-impact tests and discard low-performing ideas.
Compound learnings: Document and share insights from each test, building a knowledge base that informs future experiments.
How Growth Method Helps You Leverage the CRO Power Law
Traditional task management tools like Asana, ClickUp, or Monday.com can help organise tasks, but they fall short when it comes to managing a structured CRO programme. Growth Method is the only work management platform built specifically for growth marketers, designed to help you systematically apply the CRO power law to your marketing strategy.
Growth Method simplifies your growth marketing workflow by combining ideation, experimentation, and analytics in one powerful platform:
Ideation: Our intuitive ideation system ensures your growth ideas align with team goals and follow hypothesis best practices. Ideas are automatically categorised and shared with your team for feedback.
Experimentation: Growth Method incorporates best practices from leading growth teams, guiding experiments through clear stages—building, live, analysing, and complete—to increase velocity and maximise learnings.
Reporting: Generate sleek, professional reports effortlessly, clearly demonstrating your team's impact to stakeholders and helping you consistently prove the value of your growth marketing efforts.
With Growth Method, you can quickly identify the 20% of tests that drive 80% of your results, enabling you to focus your resources effectively and accelerate growth.
"We are on-track to deliver a 43% increase in inbound leads this year. There is no doubt the adoption of Growth Method is the primary driver behind these results." Laura Perrott, Colt Technology Services
Conclusion
The CRO power law is a powerful concept that every growth marketer should understand and apply. By recognising that most of your wins will come from a small number of tests, you can prioritise effectively, increase experiment velocity, and maximise your marketing ROI.
Growth Method is the only work management platform built specifically for growth marketers. We help companies implement a systematic approach to grow leads and revenue. Ready to optimise your CRO strategy and drive measurable results? Book a call today.
Article written by
Stuart Brameld