Interest List
Convince interested users to leave their e-mail addresses as a measure of commercial potential.
What is Interest List?
An Interest List experiment is a lean validation technique where entrepreneurs gauge market demand by collecting email addresses from potential customers who express interest in a proposed product or service. This method transforms passive interest into measurable commitment, providing quantitative data about commercial viability before investing in full product development.
The experiment works by presenting your value proposition through various channels (landing pages, social media, prototypes) and asking interested prospects to provide their email address to stay informed about the product launch. The conversion rate from visitors to email subscribers serves as a key metric for market validation. Unlike surveys or interviews that measure intent, interest lists capture actual behavior – people willing to share their contact information demonstrate genuine interest worth tracking.
When to Use This Experiment
- Early-stage validation: When you have a product concept but haven't built the full solution yet
- Market size estimation: To quantify demand in specific market segments or geographic regions
- Feature prioritization: Testing interest levels for different product variations or feature sets
- Pre-launch validation: Before committing significant resources to development or manufacturing
- Pivot decisions: When considering new market segments or product directions
- Investment preparation: To demonstrate market traction to potential investors or stakeholders
- Competitive analysis: Understanding demand compared to existing solutions in the market
How to Run This Experiment
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Define your value proposition: Create a clear, compelling description of your product/service that addresses a specific problem and target audience.
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Create collection mechanisms: Build landing pages, social media campaigns, or simple prototypes that showcase your solution and include prominent email signup forms.
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Set success metrics: Determine what conversion rates or total subscriber numbers would indicate viable market demand (typically 10-40% conversion rates suggest strong interest).
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Drive targeted traffic: Use paid advertising, social media, content marketing, or personal networks to attract your ideal customer segments to your interest collection points.
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A/B testing different approaches: Test various headlines, value propositions, or presentation formats to optimize conversion rates and understand what resonates most.
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Engage subscribers: Send follow-up emails to confirm interest, gather additional feedback, or test pricing sensitivity while maintaining engagement.
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Analyze and iterate: Track conversion rates, subscriber quality, and engagement metrics to refine your approach and validate specific market segments.
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Validate commitment levels: Consider asking subscribers for additional commitments like pre-orders, deposits, or detailed surveys to separate genuine prospects from casual interest.
Pros and Cons
Pros
- Quantifiable results: Provides concrete numbers that can be tracked and compared across different approaches
- Cost-effective: Relatively inexpensive compared to building full products or extensive market research
- Real behavior measurement: Captures actual actions rather than stated intentions from surveys
- Builds customer base: Creates a foundation of engaged prospects for future marketing and sales efforts
- Investor-friendly: Email lists demonstrate market traction that investors find compelling
Cons
- Email fatigue: Many consumers are hesitant to share email addresses due to spam concerns
- Quality vs quantity: High signup numbers don't always translate to paying customers
- Limited insight depth: Doesn't provide detailed feedback about why people are or aren't interested
- Maintenance overhead: Requires ongoing email marketing and list management efforts
- False positives: Some signups may be competitors, students, or others without purchase intent
Real-World Examples
Dropbox's MVP landing page: Before building their full product, Dropbox created a simple landing page with a demo video explaining their file syncing solution. They collected over 75,000 email addresses from interested users, validating demand for cloud storage before competing with established players. This interest list became their initial customer base and helped secure early funding.
Buffer's social media scheduling tool: Buffer founder Joel Gascoigne tested demand for automated social media posting by creating a two-page website explaining the concept. He collected email addresses from visitors interested in the solution, achieving a conversion rate that validated the business concept before writing any scheduling software. The email list provided their first paying customers when they launched.
Tim Ferriss's '4-Hour Work Week': Before writing his bestselling book, Tim Ferriss tested different titles and concepts by creating landing pages for each version and measuring email signup rates. The highest-converting title and description became the final book, which he then pre-sold to his email list, ensuring commercial success before publication.