As a Product Manager, I want to see a comparison of a current query to the same query from a previous point in time (such as the beginning of a quarter) so that I can:

• sanity-check whether tasks are Scope Creep (not in the previous query), so that I can re-triage or re-prioritize them
• differentiate between Scope Creep and Elaboration (for example, tasks that are children of tasks that were originally in scope may be Elaboration), so that I can understand the sources of scope growth and decide what to about it (e.g., re-triage, cut, adjust target date, add people)
• identify tasks that have been cut from scope, so that I can understand how much scope cutting has occurred, in order to plan how much more scope cutting may be warrented or acceptable.
• review and understand the current state of a backlog, so that I can adjust my general appetite for accepting new tasks into this project.

An example of a report satisfying these use cases:

Implementation challenges: Some users want to query on a fixed time period, e.g., current quarter. However, the date that a baseline is established is rarely the first day of a quarter, but more likely an arbitrary number of days later. Other users want to report on a periodic basis, such as vs every Monday or vs every other Monday.