Getting a startup’s engine of growth up and running is hard enough, but the truth is that every engine of growth eventually runs out of gas. Every en… - Eric Ries

Fire that customer,” I’d say to the person responsible for recruiting for our tests. “Find me someone in our target demographic.” If the next customer was more positive, I would take it as confirmation that I was right in my targeting. If not, I’d fire another customer and try again.

Zero invites imagination, but small numbers invite questions about whether large numbers will ever materialize.

The Five Whys ties the rate of progress to learning, not just execution. Startup teams should go through the Five Whys whenever they encounter any kind of failure, including technical faults, failures to achieve business results, or unexpected changes in customer behavior. Five Whys is a powerful organizational technique. Some of the engineers I have trained to use it believe that you can derive all the other Lean Startup techniques from the Five Whys. Coupled with working in small batches, it provides the foundation a company needs to respond quickly to problems as they appear, without overinvesting or overengineering.