I've been reading a lot about scrum lately, and I've found what seem to me to be conflicting information about whether or not it's ok to change the sprint backlog during a sprint. The Wikipedia article on scrum says it's not ok, and various other articles say this as well. Also my Software Development professor taught the same thing during an overview of scrum.
However, I read Scrum and XP from the Trenches and that describes a section for unplanned items on the taskboard. So then I looked up the Scrum Guide and it says that during the sprint "No changes are made that would affect the Sprint Goal" and in the discussion of the Sprint Goal "If the work turns out to be different than the
Development Team expected, then they collaborate with the Product Owner to negotiate the
scope of Sprint Backlog within the Sprint." It goes on to say in the discussion of the Sprint Backlog:
The Sprint Backlog is a plan with enough detail that changes in progress can be understood in
the Daily Scrum. The Development Team modifies Sprint Backlog throughout the Sprint, and the
Sprint Backlog emerges during the Sprint. This emergence occurs as the Development Team
works through the plan and learns more about the work needed to achieve the Sprint Goal.
As new work is required, the Development Team adds it to the Sprint Backlog. As work is
performed or completed, the estimated remaining work is updated. When elements of the plan
are deemed unnecessary, they are removed. Only the Development Team can change its Sprint
Backlog during a Sprint. The Sprint Backlog is a highly visible, real-time picture of the work that
the Development Team plans to accomplish during the Sprint, and it belongs solely to the
Development Team.
So at this point I'm altogether confused. Thinking about it, it makes more sense to me to take the second approach. The individual, specific items in the backlog don't seem to me to be the most important thing, but rather the sprint goal, so not changing the sprint goal but being able to change the backlog makes sense. For instance if both the product owner and the team thought they were on the same page about a story, but as the sprint progressed they figured out there was a misunderstanding, it seems like it makes sense to change the tasks that make up that story accordingly. Or if there was some story or task that was forgotten about, but is required to reach the sprint goal, I would think it would be best to add the story or task to the backlog during the sprint.
However, there are a lot of people who seem quite adamant that any change to the sprint backlog is not ok. Am I misunderstanding that position somehow? Are those folks defining the sprint backlog differently somehow? My understanding of the sprint backlog is that it consists of both the stories and the tasks they're broken down into.
Anyway I would really appreciate input on this issue. I'm trying to figure out both what the idealistic scrum approach is to changing the sprint backlog during a sprint, and whether people who use scrum successfully for development allow changing the sprint backlog during a sprint.
