this might be a silly question, but anyway: pretty much every article discussing burn-up and burn-down charts states that in the latter, scope changes are invisible because the chart only shows how much work is left to be done. But I do not understand - the scope creep should appear as a spike in the remaining work, shouldn't it? I understand it could mask progress (if e.g. a day was added and burnt at the same time), so in automatical reporting it might cause some issues. Otherwise, if my scope gets bigger, I would simply update the remaining work which would manifest as a spike in the burn-down chart.
3 Answers
The answer resides on the Y axis, which displays scope. On a burn up chart, when scope is added, your plan line will increase and will be visible on the Y axis. If scope is added on a burn down, the result would appear in the X axis, or extended duration. Extended duration most certainly is an indicator of scope creep but also indicates other drivers.
answered Nov 16, 2021 at 11:13
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What do you mean? If I add scope, the remaining effort increases and therefore will go up (on the Y axis). Here is what I mean (Jira burn down picture with scope added): agiledigest.com/wp-content/uploads/2018/03/…– John VCommented Nov 16, 2021 at 11:57
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See the arrow on the Y-axis? The actual line did grow but that increase could have been to in-scope work being rejected. What did not change is the overall commitment on the Y-Axis. It's hidden. On a burn-up chart, you'll see that gap in the other direction. Commented Nov 16, 2021 at 12:20
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Thanks, however I am bit confused: you said the increase could have been to in-scope work being rejected? I do not get it, rejecting items would cause an decrease.– John VCommented Nov 16, 2021 at 12:30
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If work was rejected, does it go away or does it return to backlog to get worked again? I guess it could be "de-scoped" through a controlled change but I suspect it returns to the backlog, causing the line to climb, and then reworked, causing the line to fall. No? Commented Nov 16, 2021 at 12:33
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Ok, I see what you mean. Where I work, it would be removed from active iteration and would not distort the chart. However, I think I now understand what you mean: if the total scope starts with 20 SPs, 10 are finished, then 5 added, then all is finished, I do not clearly see the delta, despite seeing the spike. I would still have an initial count of 20.– John VCommented Nov 16, 2021 at 12:56
Changes in scope are less visible in a burn-down because a single line is used to indicate both progress and new backlog items. A burn-up separates the two so that the relationship is clearer. Burn-up also shows the actual velocity whereas burn-down does not because progress appears to slow (or reverse) whenever new items are added or future estimates are changed.
Be careful about using the term "scope creep". Formally speaking, new scope is only "creep" if a change is uncontrolled/unauthorised. A burn chart shows change in the backlog or in estimates but that's usually a positive thing and is not at all the same as creep.
The key difference is that the burn-down chart has a fixed 'expected' slope, whereas the burn-up chart can change the 'expected' target line when the scope changes.
So, you are quite right that the 'actual' slope will change in both cases, but the 'expected' will only change for the burn-up chart.
Perhaps a more accurate way of describing this would be:
Scope changes are reflected in the expected target line of a burn-up chart, but they are not reflected in the expected slope of a burn-down chart
answered Nov 16, 2021 at 10:09
