Warren Buffett said that he is able to know if he is interested in buying a business in a matter of moments. Several businesses he has purchased were initiated with a phone call, letter, or meeting. Over the past 30 years he has shared his "secret" of how he filters information on his decision making process.

Buffett asks the following questions when considering an investment:
1- Can I understand it?
2- Does it have good management?
3- Does it have an enduring competitive advantage?
4- Can it be purchased at an attractive price?

Bud Labitan's book focuses on these four filters and expands on them. While Buffett has shared these ideas with anyone who would listen or read his letters to shareholders, I have not seen much written about them. Labitan has written a book just focusing on these four questions. It makes for a good refresher to experienced investors and a great starting point for those new to investing.