In Part 1 of this series, we set the frame for how to use time as a metric for assessing Agile team and project health. In Part 2, we looked at shifts in the cross-over point between burn-down and burn-up charts. In Part 3, we’ll look at other asymmetries and anomalies that can appear in time burn-down/burn-up charts and explore the issues the teams may be struggling with under these circumstances.
Figure 1 shows a burn-up that by the end of the sprint significantly exceeded the starting value for the original estimate.
There isn’t much mystery around a chart like this. The time needed to complete the work was significantly underestimated. The mystery is in the why and what that led to this situation.
- Where there unexpected technical challenges?
- Were the stories poorly defined?
- Were the acceptance criteria unclear?
- Were the sprint goals, objectives, or minimum viable product definition unclear?
Depending on the tools used to capture team metrics, it can be helpful to look at individual performances. What’s the differential between story points and estimated time vs actual time for each team member? Hardly every useful as a disciplinary tool, this type of analysis can be invaluable for knowing who needs professional development and in what areas.
In this case, there were several technical challenges related to new elements of the underlying architecture and the team put in extra hours to resolve them. Even so, they were unable to complete all the work they committed to in the sprint. The the scrum master and product owner need to monitor this so it isn’t a recurrent event or they risk team burnout and morale erosion if left unchecked. There are likely some unstated dependencies or skill deficiencies that need to be put on the table for discussion during the retrospective.
Figure 2 shows, among other things, unexpected jumps in the burn-down chart. There is clearly a significant amount of thrashing evident in the burn-down (which stubbornly refuses to actually burn down.)
Questions to explore:
- Are cards being brought into the sprint after the sprint has started and why?
- Are original time estimates being changed on cards after the sprint has started?
- Is there a stakeholder in the grass, meddling with the team’s commitment?
- Was a team member added to the team and cards brought into the sprint to accommodate the increased bandwidth?
- Whatever is causing the thrashing, is the team (delivery team members, scrum master, and product owner) aware of the changes?
Scope change during a sprint is a very undesirable practice. Not just because it goes against the scrum framework, but more so because it almost always has an adverse effect on team morale and focus. If there is an addition to the team, better to set that person to work helping teammates complete the work already defined in the sprint and assign them cards in the next sprint.
If team members are adjusting original time estimates for “accuracy” or whatever reason they may provide, this is little more than gaming the system. It does more harm than good, assuming management is Agile savvy and not intent on using Agile metrics for punitive purposes. On occasion I’ve had to hide the original time estimate entry field from the view of delivery team members and place it under the control of the product owner – out of sight, out of mind. It’s less a concern to me that time estimates are “wrong,” particularly if time estimate accuracy is showing improvement over time or the delta is a somewhat consistent value. I can work with an delivery team member’s time estimates that are 30% off if they are consistently 30% off.
In the case of Figure 2 it was the team’s second sprint and at the retrospective the elephant was called out from hiding: The design was far from stable. The decision was made to set aside scrum in favor of using Kanban until the numerous design issues could be resolved.
Figure 3 shows a burn-down chart that doesn’t go to zero by the end of the sprint.
The team missed their commit and quite a few cards rolled to the next sprint. Since the issue emerged late in the sprint there was little corrective action that could be taken. The answers were left to discovery during the retrospective. In this case, one of the factors was the failure to move development efforts into QA until late in the sprint. This is an all too common issue in cases where the sprint commitments were not fully satisfied. For this team the QA issue was exacerbated by the team simply taking on more than they thought they could commit to completing. The solution was to reduce the amount of work the team committed to in subsequent sprints until a stable sprint velocity emerged.
For a two week sprint on a project that is 5-6 sprints in, I usually don’t bother looking at time burn-down/burn-up charts for the first 3-4 days. Early trends can be misleading, but by the time a third of the sprint has been completed this metric will usually start to show trends that suggest any emergent problems. For new projects or for newly formed teams I typically don’t look at intra-sprint time metrics until much later in the project life cycle as there are usually plenty of other obvious and more pressing issues to work through.
I’ll conclude by reiterating my caution that these metrics are yard sticks, not micrometers. It is tempting to read too much into pretty graphs that have precise scales. Rather, the expert Agilest will let the metrics, whatever they are, speak for themselves and work to limit the impact of any personal cognitive biases.
In this series we’ve explored several ways to interpret the signals available to us in estimated time burn-down and actual time burn-up charts. There are numerous others scenarios that can reveal important information from such burn-down/burn-up charts and I would be very interested in hearing about your experiences with using this particular metric in Agile environments.