Which chart is useful for showing trends over time based on iterations completed by the project team?

A velocity chart is particularly useful for illustrating trends over time based on the quantity of work completed in iterations, typically in agile project management contexts. It visually represents the amount of work that a team has completed during each iteration or sprint, measured in units such as story points or hours.

By plotting the completed work over successive iterations, the velocity chart helps project managers and teams track their performance and capacity. This can provide insight into how much work the team can typically handle, allowing for better planning and forecasting for future iterations. Changes in the trend can indicate improvements or issues within the team's performance, thus providing valuable information for retrospectives and future planning sessions.

In contrast, a burnup chart shows the amount of work completed versus the total amount of work over time, and a burndown chart tracks the amount of work remaining in a sprint or project, focusing on how much work is left to complete. A control chart is more focused on process stability and variability over time rather than iteration-specific work completion, making it less suitable for assessing trends tied to project iterations.