Context: 
I have an expected/predicted end date on a variable in my process. 
I want to 

a) Filter only for instances which completed within the expected time 

Variable date filters display additional operator selections 'More than.../Less than...'
Secondary selection allows date options 'Process Start Date / End Date' 

Result: Only the instances which match the criteria will be displayed. 
User can view the instance id's via the saved Report raw data view and reaserch them further in other tools such as cockpit. 

b) Create a comparison report displaying the above against the total number of instances 

Duplicate process definition. 
On one duplication apply the previously mentioned filter. 
Group this Report by process and view the differences in counts. 
it is also possible to use a secondary grouping to view trends over time for example, by grouping by end date and distributing by process. 

 (This is dependent on the linked ticket below) 

c) View durations of the process instances

By using a duration measure, it is possible to view durations of the instances. Add a goal line for the expected duration for reference. 

Design -> https://zpl.io/boAp7wW 

Reach out to BT to validate the concept once this is prioritised for (hopefully) the next quarter. 

Support 
https://jira.camunda.com/browse/SUPPORT-10165 
https://jira.camunda.com/browse/SUPPORT-9862 

https://jira.camunda.com/browse/OPT-4920