I’m sure you are proud of your products. After all, you pour your creative genius into each one. If they are that good, why not offer a money back guarantee? If they are not that good, why sell them?
Before a publisher commissions a new book, he must be able to answer three absolutely fundamental questions about the project. If he can’t, the project is likely doom to failure.
It’s normal to measure your performance. After all, unless you know how you are doing it is very hard to improve. However, like me, you’ve probably been measuring the wrong thing…