Learning Objectives
By the end of this lesson you will be able to:
- Read a Burndown chart and identify five warning patterns
- Explain what a Cumulative Flow Diagram (CFD) shows and how it differs from a Burndown
- Identify three common CFD shapes and what each signals about team workflow
- Describe when to use each chart and what actions each pattern suggests
The Burndown Chart
A Sprint Burndown chart shows remaining work (usually Story Points or task count) on the Y axis against time (sprint days) on the X axis. The ideal trend is a diagonal line from "all work remaining" on Day 1 to "zero work remaining" on the last day.
Reality is never a clean diagonal. The art is reading what the actual line shape tells you.
Five Warning Patterns
Pattern 1: The Flat Line Work isn't burning down. The line stays flat for 2-3 days.
Signal: The team is blocked. Something is preventing completion. Could be a blocker, a dependency on another team, or work that started but can't finish without something external.
Action: Bring it to the Daily. Name the blocker explicitly.
Pattern 2: The Late Cliff The line is flat until day 8 of a 10-day sprint, then drops suddenly.
Signal: Everything "finished" on the last day or two. This is the partial-credit pattern in action — stories were almost done all along, the team just wasn't marking them complete. Or: there's a manual deployment/release step happening only at end of sprint.
Action: Investigate the definition of "Done". Is there a step (code review, deployment, QA sign-off) that only happens at sprint end?
Pattern 3: The Stepped Staircase Work burns down in chunks, with flat periods in between.
Signal: The team is finishing things in batches, not continuously. Often signals large stories that take multiple days, or a process where work can't be closed until a batch review.
Action: Slice stories smaller so work can be completed and marked Done daily.
Pattern 4: The Upward Spike The line goes up (remaining work increases) mid-sprint.
Signal: Scope was added to the sprint. This should be rare and explicit. If it's happening every sprint, the sprint backlog isn't being protected.
Action: Review the sprint commitment process. The Scrum Guide says the sprint backlog is owned by the team — external additions require team agreement.
Pattern 5: Burndown Below the Ideal Line (Too Fast) The team is burning faster than expected and will finish days early.
Signal: Under-commitment. The team put less into the sprint than they could handle, possibly because of risk aversion or inflated estimates.
Action: Good news, but worth investigating. Pull in stories from the backlog.
The Cumulative Flow Diagram (CFD)
A CFD shows the count of items in each workflow state (Backlog, In Progress, Review, Done) over time, represented as stacked bands. Unlike the Burndown, it covers multiple sprints and reveals flow health.
Reading the CFD
- Band width at any point = number of items in that state at that time
- Widening "In Progress" band = WIP is growing, team is starting more than finishing
- Flat "Done" band = no work is being completed; team is stuck
- Narrowing gap between "In Progress" and "Done" = work is flowing well
Three Common CFD Shapes
Shape 1: The Funnel Bands narrow progressively toward "Done". Healthy flow.
What it means: Items are moving through the system efficiently. Bands are proportional and stable.
Shape 2: The Ballooning Middle The "In Progress" or "Review" band keeps expanding over time.
What it means: There's a bottleneck in that state. Work enters but doesn't exit. Common cause: too few reviewers, QA is a bottleneck, or the definition of "Ready for Review" is unclear.
Action: Identify where the work is accumulating and remove the constraint.
Shape 3: The Frozen Dome The "Done" band stops growing. Everything else continues.
What it means: The team is busy but not completing. A major blocker exists, or the Definition of Done is so strict that very little crosses the line.
Action: Urgent — investigate the blocker and potentially renegotiate the DoD.
Burndown vs CFD: When to Use Which
| Burndown | CFD | |
|---|---|---|
| Scope | Single sprint | Multiple sprints / release |
| Shows | Remaining work over time | Flow rate by state over time |
| Best for | Sprint health monitoring | Process bottleneck diagnosis |
| Limitation | Doesn't show WHERE work is stuck | Doesn't show urgency within a sprint |
Pro Tip: Run both. Use the Burndown in your Daily to monitor sprint health. Use the CFD in your retrospective to diagnose systemic issues.
Summary
Charts don't manage projects — people do. But charts tell you where to look. A flat Burndown tells you to find the blocker. A ballooning CFD tells you to find the bottleneck. Reading these patterns fluently turns you from someone who reports problems into someone who spots them before they become crises.