The rate of growth depends primarily on three things: the profitability of each customer, the cost of acquiring new customers, and the repeat purchas… - Eric Ries

This is an old direct marketing technique in which customers are given the opportunity to preorder a product that has not yet been built. A smoke test measures only one thing: whether customers are interested in trying a product. By itself, this is insufficient to validate an entire growth model. Nonetheless, it can be very useful to get feedback on this assumption before committing more money and other resources to the product.

Part of the special challenge of being a startup is the near impossibility of having your idea, company, or product be noticed by anyone, let alone a competitor.

Most important, a disciplined team can experiment with its own working style and draw meaningful conclusions.