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Mean Time to Failure

N

Nikesh Valji

New Member
Hi Everyone,

I have a question on a formula. I have to calculate the mean time to failure. Attached is a file where I have the number of times a bike has had to come in to be fixed from Jan - Aug 2013. What I need to calculate is once it has been in for the first time in 2013, how long until it was next in?

As you can see these bikes have been repaired at different times and I need a formula that will work on all lines.

I would appreciate anyone that can give me some help or any pointers.

Many thanks,

Nikesh
 

Attachments

Hello Nikesh,
Welcome to the forum!

Can you add in some calculated values for the sample data you uploaded? For example, for the first data row, would the MTF be (zero) 0 months since the bike was repaired in January and again in February?

-Sajan.
 
Hi, Nikesh Valji!
Joining Sajan doubts, are you sure you want to measure the MTTF in months and not in days?
Regards!
 
Hi All,

I have the data by month so it would be better if I could just have MTTF by month.

Attached is a sample of what I would ideally like to see.

Hope this helps to clarify.

Many thanks,

Nikesh
 

Attachments

Hi Nikesh,
Good that you uploaded a sample file. It would also be helpful to add in some explanations of how you calculated the values you supplied. I can guess, but I would rather you describe them to be certain we are addressing your problem.

Cheers,
Sajan.
 
Hi Sanjan,

I updated it based on the time between each visit after the first visit for the bike. In the example I provided, I have given an explanation to say:
First Instance: Jan-Feb - 1 month
Second Instance: Feb-Mar - 1 month
Third Instance: Mar-May - 2 months
Fourth Instance: May-Aug - 3 months
The mean time between each visit is 1.75 months

I hope this helps.

Many thanks,
Nikesh
 
Hello,
Here is one approach you could try.

Enter the following array formula in cell M3, and copy down:
=AVERAGE(IFERROR(1/(1/(FREQUENCY(COLUMN(E3:L3),IF(E3:L3,COLUMN(E3:L3)))-IF(E3,ROW(OFFSET(A$1,,,COUNT(E3:L3)+1))=1))),FALSE))
Enter with Ctrl + Shift + Enter

Cheers,
Sajan.
 
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