Below is a fancy release burnup chart (click it to see the full image) that visually shows the work of a team from a recent release by a LeadingAgile client.
The red line effectively is the amount of risk. You can see that the team started the release with about 50% of their stories unsized, but consistently drove that down through the first half of the release.
You can see the impact of end-of-release hardening in the flatness of the shaded blue area on the right side of the chart.
In the shaded gray area, you can see the team performing backlog grooming, breaking down the work into estimated stories and even cutting scope mid-release (the gray area increases as the red line decreases).
The flatness of the shaded blue area early in the release shows the impact of a backlog that isn’t well-groomed, but as the team drove that red line down, the blue area takes on a more-consistent positive slope.
Cool stuff that demonstrates the impact of a groomed backlog and the effectiveness of a team.