This request/question was posed by Atlassian staff in JRA-24973.

I would like to be able to filter issues based on the number of sub-tasks related to each issue. This would allow me to find which issues currently have no sub-tasks when they should, per our internal process, and which issues may have too many sub-tasks and should be broken down into smaller issues.

Currently, the only way I can determine which issues do not have sub-tasks is to ORDER BY subtasks DESC on the Issue Navigator screen, but this does not satisfy on-going reporting on a dashboard through the Two-Dimensional Filter Statistics gadget, for example.