Use average lines to understand performance better
How to configure average line
To configure average lines, first of all, switch on toggles for respective sprint metrics. For example, we would like to see average lines for "Final commitment" and "Completed work" metrics on the screenshot below. The average line is calculated as the moving average of 2 last sprints.
We recommend switching on average line toggles for two or fewer sprint metrics as the velocity chart may become cluttered and hard to analyze.
The average line can be configured in two ways:
As a simple average of all sprints that appear on the chart
As a moving average of a selected number of sprints (see how it is calculated)
How to analyze the chart
How moving average is calculated
Average lines on the chart above are configured as “2 sprints” moving average. Let’s take a look at the green line for Completed work and check how the “2 sprints” moving average is calculated:
Sprint | “Completed work” value | Moving average value | Calculation formula |
|---|---|---|---|
Sprint 1 | 31 | n/a | there are no two sprints to calculate the moving average |
Sprint 2 | 31 | 31 | = (31+31)/2 |
Sprint 3 | 28 | 30 | = (31+28)/2 = 29.5 which is rounded to 30 |
Sprint 4 | 28 | 28 | = (28+28)/2 |
Sprint 5 | 35 | 32 | = (28+35)/2 = 31.5 which is rounded to 32 |
Sprint 6 | 24 | 30 | = (35+24)/2 = 29.5 which is rounded to 30 |
How to read the chart with moving average
“Completed work” moving average line
From the chart above, we see that team Alpha’s actual velocity (moving average line for Completed work metric) fluctuates from 28 to 32 story points. The team’s performance is more or less stable; therefore, the amount of work the team can deliver is predictable, which is good.
“Final commitment” moving average line
From the chart, we see that Final commitment significantly fluctuates: from 34 SPs in Sprint 2 to 44 SPs in Sprint 4 and then back to 36 SPs in Sprint 6. This happens because the sprint’s scope is constantly amended by adding new work and changing estimates while a sprint is active (see “Added work“ and “Estimation change” metrics on the chart).
At the same moment of time team’s velocity is pretty much stable at around 30 SPs (“Completed work” metrics). So, the team needs to take action in three areas:
Analyze reasons why the work is added while a sprint is active
Analyze what can be improved in sprint planning and estimation so that work is not frequently re-estimated during the sprint
Remove some work from the sprint’s scope. The team knows its velocity, velocity is stable, and the team knows that it is not capable of delivering excess work.
Our recommendation on average line types
In our humble opinion, in most cases, a moving average is a more actionable type of chart than a simple average line.
Here is the same velocity chart with a simple average line; it’s a horizontal line, the value of which is calculated based on sprints visible on the chart: