What is the difference between 'Original estimate' and 'Sigma original estimate'?

[Tim Gleeson]

We thought the sigma fields would sum linked items for an epic, as well as provide a net remaining hours on the original estimate. However, it is not working that way. The data we are inserting in original estimates is coming out the same on 'Original estimate' and 'Sigma original estimate', and the 'Sigma remaining estimate' is not accounting for time logged on linked issues.  

[Alex Koxaras _Relational_]

Hi @Tim Gleeson 

The Σ-Original Estimate, doesn't work on Epics. It's only for the parent-child relationship. Issue under Epics have a different relationship than that of the parent-child.

You can read this post of mine https://community.atlassian.com/t5/Jira-Software-articles/Calculate-the-sum-of-original-estimates-of-all-issue-types-to-an/ba-p/1660572 on how to calculate both original and remaining estimate on Epics, using jira automation.

[Tim Gleeson]

Many thanks Alex. I remain confused, as it looks as if both Σ-Original Estimate and Original Estimate both work on epics and other items. Check this screen shot, particulary the row with the epic. You can see that both the Σ-Original Estimate and Original Estimate are reporting on the epic. 

My view currently is that Jira is not supporting any field customisation by issue type. It says it does, but I can find no way to make that work. Any way to guide me through this would be appreciated

[Nic Brough -Adaptavist-]

The Σ fields only add up the field on the current issue and its sub-tasks.

The thing that is not clear here is that child issues of Epics are not sub-tasks, but you can create sub-tasks on Epics.

Key	Ownership	Original estimate (h)
ABC-123	Epic	1
ABC-126	sub-task of ABC-123	2
ABC-139	sub-task of ABC-123	3
ABC-456	Epic	4
DEF-123	Child story of ABC-456	5
ABC-457	Child story of ABC-456	6

Then the Σ-Original Estimate's on the epics will be

ABC-123: 6  (1 + 2+3 from the Epic's sub-tasks)

ABC-456: 4  (Just the 4 that's on the Epic)

If you want to sum up estimates to an Epic, you are going to need to create a field for it and automate, script, or find an app to do it.

[Tim Gleeson]

Many thanks Nic. This is helpful. By sub-task of the epic, do you mean items which are linked to the epic? Or do you mean child tasks that are not stories?

The main thing for us is Σ-Time Spent. We need to aggregate time spent on items linked to an epic. and we need to aggregate time spent on child items to a parent. 

Is there any difference here between Σ-Time Spent and Time Spent? These fields cannot be configured by issue types, they can only be configured by issue type schemes, which makes it very difficult for us.

Any guidance is appreciated. Thanks

[Nic Brough -Adaptavist-]

A sub-task is a fragment of its parent base-level issue.  A base-level issue type (story for example) can be included in an Epic.

Now the quirk here - Epics are a modified base-level issue at it's heart, so it can have sub-tasks as well as linked base-level issues.

"Σ-Time Spent" and "Time Spent" are calculated fields (behind the scenes, they're not even fields, but that is not important here)

Time spent is the a sum of all the work logged on the current issue.   Σ-Time Spent is the sum of all the work logged on the current issue and all of its sub-tasks.