These are typical burn-up charts for a chosen two-week iteration. The left one shows estimated total scope (green and blue) and the completion curve (orange). The right one shows actual time spent on tasks altogether (blue) and on complete tasks (orange).
You can see some interesting points on the graphs, marked with numbers 1, 2, 3 and 4:
- Initial growth of estimates during the iteration planning. First one or two days are dedicated to sketching the design, breaking stroies into tasks and giving them estimates
- Growth of estimates due to new urgent stories (they always appear, you know)
- Drop of estimates due to removal of less urgent stories from the iteration
- Difference between estimated and actual time