The grim reality is that most start-ups fail. Most new products are not successful. Yet the story of perseverance, creative genius, and hard work persists.

Customers don't know what they want. There's plenty of good psychology research that shows that people are not able to accurately predict how they would behave in the future. So asking them, 'Would you buy my product if it had these three features?' or 'How would you react if we changed our product this way?' is a waste of time. They don't know.

The goal of a startup is to figure out the right thing to build-the thing customers want and will pay for-as quickly as possible. In other words, the Lean Startup is a new way of looking at the development of innovative new products that emphasizes fast iteration and customer insight, a huge vision, and great ambition, all at the same time.

Progress in manufacturing is measured by the production of high quality goods. The unit of progress for Lean Startups is validated learning-a rigorous method for demonstrating progress when one is embedded in the soil of extreme uncertainty.

There is much that public policy can do to support American entrepreneurs. Health insurance reform will make it easier for entrepreneurs to take a chance on a new business without putting their family's health at risk. Tort reform will make it easier to take prudent risks on new products in a number of sectors.

Start-ups make so many mistakes that the challenge to identify the root cause of a failure is tough. But believing in your own plan is probably the worst.

If you don't know who your customer is, you don't know what quality is.