How does Sprint Health Gadget calculate Scope change?

[Toivo Vaje]

The Sprint Health Gadget that was introduced in Greenhopper 6.2 displays a percentage value for scope change. How is this value calculated?

If I start a Sprint with 100 points, drop stories worth 20 p and add something else worth 20 p, what is my scope change percentage?

https://confluence.atlassian.com/display/GH/Using+the+Sprint+Health+Gadget

[Toivo Vaje · Accepted solution]

Based on empirical testing, the value is just the number of points currently in Sprint scope versus number of points originally in the sprint scope.

So as an answer to my question, 100 p + 20 p - 20 p would result in a scope change of 0 %.

[Matthew Duff]

Can anyone justify why this seems to be the formula used?  It seems to me that a more logical solution would be:

scope change = (absolute value of story points added OR removed) / (# of story points originally committed to in the sprint)

Using this formula would yield a scope change of 40%, as the absolute value of 20 story points added and 20 story points removed is 40 story points.

[Deleted user]

hmm, this is confusing me too.

We had 19 points at the start of our sprint, added 5 issues worth 5pts in total, and it is saying 53% scope change. How?

[Tim Keating]

Are you certain that your board is set up to estimate in story points? Even if you're tracking story points, it might be configured for e.g. issue count.

[Deleted user]

Definitely. We have 6 teams that have been using agile boards for 4 months. Generally the calculations seem ok, but this is definitely wrong.

I think it's a combination of adding/removing things from sprints, changing story points, is causing something to go wrong somewhere.

There's also a problem with the velocity vs sprin/burndown report calculations.

https://answers.atlassian.com/questions/131984/sprint-report-does-not-match-velocity-chart-bug?page=1#comment-310075

I wish someone from Atlassian could give a definitive answer as to how these calculations should work - it would then be a lot easier to work out what's wgoing wrong.

[Jonathan Ginter]

Atlassian is trying to capture the impact on the velocity of the team, which an absolute value would not reflect. Only the overall rise or fall in the total points would help to highlight that.

The only other reason to track scope change would be to highlight the two basic root causes...

• Poor planning / estimation techniques - this results in issues that are not well understood before they are added to the sprint, which can cause estimates to increase or decrease or for the story to be removed
• Poorly managed business priorities - this can cause issues to be added or removed

An absolute value would not help shed light on either of these, since it only looks at the pure rise and fall of points and not the underlying reasons for that behavior.

[Jonathan Ginter]

You might also want to take a look at this thread, which highlights some additional key points about how the start time of your sprint can impact the calculation...

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