Compare two collections of the same dataset

[jpmckinney]

For OCP's organizational targets, we track the number of publishers that have improved their publications. To do this using the DQT, we'd need to be able to either directly compare check results and/or aggregate check results into higher-level figures, to be able to determine, e.g. "publisher X improved" and "the improvement is accounted for by improvements on these specific checks, though the quality deteriorated on these other checks."

A dependency is having Kingfisher do scheduled collections, which is currently blocked by Kingfisher Views burning through hard drives (issues tracked in Trello).

Earlier feedback:

Charlie: I want to be able to compare DQT outputs over time. (+1: OH)
Charlie: I want to be able to automatically compare the current DQT results with a previous one e.g. a table with current results vs previous results and indication of changes. (+1: NP)

On a related note, Oscar mentioned:

This may go beyond the scope of the project but having some sort of benchmark would be helpful. The idea, if at all possible, would be to draw comparisons with other countries.

[jpmckinney]

From open-contracting-archive/pelican#20

a chart of objects per stage over time (by year) - as an analyst, I want to see objects published over time so that I understand how a publisher's content has evolved over time with respect to publishing across all stages of procurement.