Stage 2
If users do not return, the product has not cleared the stage.
Use this stage to separate real pull from launch momentum, incentives, and founder-driven demand.
Use this once users exist and retention, demand, or payment is still uncertain.
System Flow
Problem → Product → Model
Problem
Problem–Solution Fit
If the problem is weak, every signal above it misleads.
Product
Product–Market Fit
If users do not return, you do not have product–market fit.
Business Model
Business Model Fit
If margins break at scale, the model fails.
If one breaks, everything above misleads
- Product signals are invalid without a real problem.
- Business signals are invalid without real product pull.
Current Stage
Use this stage once real users already exist
Product–Market Fit
If users only respond to pressure, the product has not reached fit.
When to use
After early usage appears, but before scale spend, team expansion, or channel ramp.
How ProductBooks works
- Run the evaluator.
- Identify what still scores zero.
- Generate the missing evidence.
- Re-run the same stage before moving on.
What this stage decides
Keep the decision boundary narrow. Everything outside it stays outside.
Decides
Whether users return without external prompting.
Does not do
Validate growth tactics.
Decides
Whether demand extends beyond launch noise.
Does not do
Predict total market size.
Decides
Whether payment behaviour is real, not stated.
Does not do
Help you "pass".
Evidence Rules
Strict rules only. No interpretation layer.
What counts
- Organic retention before prompted activity.
- Repeatable demand before campaign spikes.
What fails fast
- Observed payment behaviour before pricing opinion.
- Missing proof still blocks progression.
Generate Missing Evidence
Operators generate proof. They do not soften the verdict.
Demand Reality Operator
GENERATEObserve whether new users arrive through repeatable channels without founder push.
Used to improve
The scoreable gaps this evaluator surfaced.
Payment Conversion Operator
GENERATEObserve whether users accept or reject a fixed paid offer.
Used to improve
The scoreable gaps this evaluator surfaced.
Retention Without Reminders Operator
GENERATEObserve whether users continue without reminders, nudges, or follow-up.
Used to improve
The scoreable gaps this evaluator surfaced.
Organic Pull Operator
GENERATEObserve whether users create demand through unsolicited referrals.
Used to improve
The scoreable gaps this evaluator surfaced.
Run Product–Market Fit
Start with evidence you can show. Missing proof still scores zero.
What to do next
Move to Business Model Fit only after product pull is real.
Once users return and pay without pressure, test whether the economics can support scale.
Go to Business Model Fit