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Create a second calculated field to convert ms to min:
This field converts the "Time to first response: Elapsed (ms)" to minutes. The expression is:
MULTIPLY(DIVIDE(Time to first response: Elapsed, 60000), 1)
This formula converts the elapsed time from milliseconds to minutes.
Create a third calculated field for average time to first response in minutes:
This field replicates the "Time to first response: Elapsed" but in minutes. It is based on the first and second calculated fields. The expression is:
MULTIPLY(DIVIDE(Time to First Response(in min), Count of issues), 1)
This formula calculates the average time to first response in minutes.
Add the calculated field to the report:
Create a report by selecting the field "Average Aggregation (in min)" instead of "Time to First Response: Elapsed (ms)".
Run and save the report. The results should now display correctly with both sum and average values as shown in the below screenshot.