Changing parent issue from subtask increased my hours' burndown

Question

Guys, I have a question about the Burndown Chart related to Remaining time estimate.

I am working in a current sprint and found a necessity to divide one story, so I've created two new stories inside the sprint.

After that, I've moved 2 sub-tasks (with estimated time defined) from the original story, each one for the new stories created.

Then, my burndown increased, and checking the activities, it shows (from the report):

scope change - Issue added to sprint - Increased 2h (the remaining time defined in the issue).

If I've just changed the parent issue (moving the sub-taks from one story to another (new one)), why it affected my burndown? Is it correct?

If yes, how is the best way to move one subtasks between stories and not impact the burndown?

Obs: Sorry for my english, but if something is not clear please let me know.
Tks.

vsabadoti_cit · Answer

The original story decreased the remaining time, and the new one has the remaining according their sub-tasks included. Looking the burndown, just increased the remaining after move these sub-tasks.

vsabadoti_cit · Answer

The team started the sprint with one story that contains 60hs estimated and I realized that we can divide this single story in more small stories.

So, I created more stories inside the sprint and moved the sub-tasks from the original story to the new ones.

I imagined that simple change sub-tasks between stories inside the sprint could not impact the burndown.

Phill Fox · Answer

When you created your two new stories and added them to the sprint, this would cause a change in the sprint scope and so your burndown estimate would be changed. Moving the subtask to the new story will cause that remaining time to be added. The original story could still be showing the remaining time from when the subtasks were associated with it. I would check what remaining time is now shown against the original story and if necessary manually adjust that to take account of the movement of the subtasks.