I need to calculate the median of the response time and resolution time for all the incidents of a month.

[Swadesh Saraf2]

I need to create a report/score which will show the median value of the response time of the resolved incidents for a month. Has anyone done something similar or can guide me on how to achieve it?

[Thomas_Davis]

Take a look at the OOTB Incident SLA Management Indicators:
https://docs.servicenow.com/bundle/newyork-performance-analytics-and-reporting/page/use/dashboards/r...

If you are not able to find what you need OOTB, I would suggest that you use the SLA feature to accomplish this. You can create SLA's to monitor both response and resolution times. You may already have an SLA Definition created that you could use.
https://docs.servicenow.com/bundle/newyork-it-service-management/page/product/service-level-manageme...

In the Filter Navigator search for SLA and you will see everything that comes in the Instance for it. The admin role is required to create SLA's.

Hope this helps or points you in a good direction,