Does a big waitlist prove people want my product?

Because joining one is free. People sign up out of curiosity, to be polite, or because a post caught them at the right moment. None of that says they would change what they do today, or pay.

Rob Fitzpatrick's The Mom Test (2013) gives a useful rule: a conversation only moves you forward if the other person gives up something. He names three currencies: time, reputation and money. A waitlist sign up spends almost none of the three.

Ask the list for something that costs a little:

• Time: a twenty minute call about how they handle the problem today.
• Reputation: an introduction to a colleague who has the same problem.
• Money: a deposit, a preorder or a paid pilot, which is a small, time-boxed trial with real customers.

Count how many say yes. That number is worth more than the size of the list.

Yes, as a smoke test and as a contact list. A smoke test is a simple page that describes the product before it exists and measures whether people act. If almost nobody signs up, that is real evidence against the idea. If many do, you have found people to ask the harder questions.

Look at where sign ups came from and what they did next:

1. Separate sign ups from one viral moment from steady ones.
2. Check who opened your follow up email and who replied.
3. Note anyone who asked about price or timing without being prompted. They are your first pilot candidates.

For a fuller way to rank the evidence you have, see is my idea good or am I just excited.

Idea Validator returns a verdict of Build it, Sharpen it or Kill it, your riskiest assumption and a test for it. It helps you decide what to ask your waitlist, so the list turns into evidence.

Email your ten most recent sign ups. Ask each for one thing: a short call, an introduction or a small deposit. Count the yeses.

• Rob Fitzpatrick, The Mom Test, 2013.