What can I learn from an Open by Priority chart?

Dynamic planning is most effective when you know the relative priorities of work items you are tracking. The Open by Priority chart helps you check that your team is working on the optimal mix of artifacts.

Use the Open by Priority chart for a quick overview of the type of work your project is working with. A glance at this chart can suggest some broad generalizations, which you'll then want to test by examining your planning folder contents more closely.

When the darker bars on the left side of the chart are high, you are probably working on the high-impact issues that come up earlier in a work cycle. Don't be surprised if the trend line in your Burndown chart is not yet sloping steeply downward to the right.
When the lighter bars on the right side of the chart are high, you are likely to be working on cleanup issues and refinements. You may be approaching the end of the work cycle you defined in this planning folder. At this stage, the Closed slice of the Open vs. Closed chart is likely to be equal to or larger than the Open proportion.

Note: The Open by Priority chart won't tell you how much work is involved in the artifacts that it measures. For that, check the Burndown chart.