I new to Scrum and while I understand the team concept behind the Sprints, I imagine there still needs to be a guardian for the team who minimizes the interference from Product Owners who are not conversant in software development. What are your successes, and what horror stories have you lived through?
Update:
I am looking for the balance between coding to implement business process vs creating the appropriate architecture for a client. If the product owner is from the business unit there has to be guidance as to what amount of time should be spent on data model, etc.
Definition:
By "out of control" product owner I mean typically some one from the business unit who aggressively sets time frames while having no real technical ability to create that estimate. Typically this person will say: "I need those screens before the next meeting with the Operating Committee next week, so prioritize those work products first. We'll tackle the database after we talk to Operations."
Great answers everyone. Thanks for the good input.
"there has to be guidance as to what amount of time should be spent on data model, etc."
Right. That's what prioritization is all about. You define the work, you prioritize. You work according to the priorities.
What can get out of control?
Redefining the work before anything gets done?
Redefining the priorities before the work gets done?
The solution is the same. Break the work into smaller pieces so something gets done before there's an opportunity to make a change.
If you have short (2-week) sprints, it's not possible to be out of control. If you go for slightly more practical 4-week sprints, then you have a small chance of getting into trouble.