Determine how many units of a certain type failed within a given time period.

I put the days in row 1 (i.e. 30,60,90, 180, etc)
In C3 copied down

=SUMPRODUCT(--(Data!$C$2:$C$300=$B3),--((Data!$B$2:$B$300-Data!$H$2:$H$300)<C$1))

In D3 copied across and down

=SUMPRODUCT(--(Data!$C$2:$C$300=$B3),--((Data!$B$2:$B$300-Data!$H$2:$H$300)<D$1))-SUM($C3:C3)
Does that work for you?
Is something else factored in to get your 359 failures or is that based on a bigger data set?

Hello ChemistB,

Thanks for your help. The data i attached was only a subset....I've attached all the data.

I used your formula above while changing the cells/etc. to the master sheet but my numbers show up negative/etc. Believe I've got a mistake in my formula but wanted you to review.

Update: 10:33am PST

I was able to get the data to look clean however I believe I am still missing some of the data from the Summary tab as the total sum in the summary table does not equal the total # of rows in the "High_AC_Alarms" tab.

Also, is the formula correct for the last column where the "Failed >24 Months of Install" ? These are ones that should be greater than 24months.

Thoughts?

Example.xlsx

You're right, that last column should be

=SUMPRODUCT(--(High_AC_Alarms!$P$2:$P$30000=Summary!B3),--((High_AC_Alarms!$I$2:$I$30000-High_AC_Alarms!$X$2:$X$30000)>=Summary!I1))

On some of the others, you didn't have the cells anchored properly with your $.

Your sheet is set to "Manual calculation" so you need to hit F9 to calculate. Attached is the corrected sheet. There are 731 rows of 503 on "High_AC_Alarms and the sum across row 3 in Summary is 731.