# Date Diff for Matching Column Entries

Hi guys,

I am trying to create a calculated column to find the Mean Time Between Failures.

I have one column that has the equipment numbers and another which displays the malfunction start date.

This new column should find the matched up equipments and then calculate the time difference, in days, since the last entry. I tried doing a simple if statement but my result kept giving me zero days. Any help would be greatly appreciated. So the COLUMN equipment numbers should be matched up and the date difference between the ROWS of those matched columns is what I'm interested in.

EDIT: This doesn't necessarily have to be a calculated column, this could be on the category axis of a visualization too. I am looking at possible OVER functions but still can't figure it out...

Thank you for your time