"Perhaps you’ve read a book, on Extreme Programming and have decided that is the right approach for your company. Or maybe you attended a Certified ScrumMaster training course and think Scrum sounds good. Or maybe you read a book on a different agile process, and it sounds perfect for your organization. In all likelihood, you’re wrong."
Reference: “Succeeding With Agile”, Mike Cohn, Addison-Wesley, 463 pages, IBSN 978-0-321-57936-3