Here is the general concept.

I have 56 Televisions. The month is currently april and 3 of those 56 have
failed(quit, don't work). I am wanting to try and find a quick and easy
formula that gives me the rate of failure. I know it is probably something
simple, though it seems all brain power has left me on a friday.

56 Television
3 Quit
4 Months into the year
Televisions are 1997 or older
2 different kinds -- Magnavox and Phillips.

I have a spreadsheet all laid out, though I just can't seem to think of the
way to tie it all together. I would like to show the rate of failure between
the two brands as well. 2 of those 3 are Magnavox's, and the other 1 is
Phillips. Any help would be -greatly- appreciated!

Thanks ahead of time!

David,

You don't say how your data is laid out, so I can only give you a general answer

C Count of televisions
F Failure count
P Period of failures, in days


= F * (365/P) / C

The above will give the fraction that would have failed in a year at the current rate. For
a percentage, format for % or multiply by 100.

= F * (365/P) / C * 100

For the period, subtract the beginning and end dates:

= F * (365/(enddate - startdate) / C * 100

You need only replace F, enddate, startdate and C with the cells of your data.
--
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com
-----------------------------------------------------------------------
"David M" wrote in message
...
Here is the general concept.

I have 56 Televisions. The month is currently april and 3 of those 56 have
failed(quit, don't work). I am wanting to try and find a quick and easy
formula that gives me the rate of failure. I know it is probably something
simple, though it seems all brain power has left me on a friday.

56 Television
3 Quit
4 Months into the year
Televisions are 1997 or older
2 different kinds -- Magnavox and Phillips.

I have a spreadsheet all laid out, though I just can't seem to think of the
way to tie it all together. I would like to show the rate of failure between
the two brands as well. 2 of those 3 are Magnavox's, and the other 1 is
Phillips. Any help would be -greatly- appreciated!

Thanks ahead of time!

Could you give me a better layout. It seems I'm just either too dumb to put
it together, or simply am not selecting the right fields. Though your "C" and
"F" and etc is simple, I get an error. I'm using Excel 2007, btw.

Current Layout:
Date(A2) Brand (B2)
01/01/08 Magnavox (B3)etc
03/02/08 Phillips
04/25/08 Magnavox

Current Month: April (D9)
Total Failed this year: 3 (D10)
Total TVs: 56 (D11)
Rate of Failu ---(D12)
Percentage Failed: ---(D13)




"Earl Kiosterud" wrote:

David,

You don't say how your data is laid out, so I can only give you a general answer

C Count of televisions
F Failure count
P Period of failures, in days


= F * (365/P) / C

The above will give the fraction that would have failed in a year at the current rate. For
a percentage, format for % or multiply by 100.

= F * (365/P) / C * 100

For the period, subtract the beginning and end dates:

= F * (365/(enddate - startdate) / C * 100

You need only replace F, enddate, startdate and C with the cells of your data.
--
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com
-----------------------------------------------------------------------
"David M" wrote in message
...
Here is the general concept.

I have 56 Televisions. The month is currently april and 3 of those 56 have
failed(quit, don't work). I am wanting to try and find a quick and easy
formula that gives me the rate of failure. I know it is probably something
simple, though it seems all brain power has left me on a friday.

56 Television
3 Quit
4 Months into the year
Televisions are 1997 or older
2 different kinds -- Magnavox and Phillips.

I have a spreadsheet all laid out, though I just can't seem to think of the
way to tie it all together. I would like to show the rate of failure between
the two brands as well. 2 of those 3 are Magnavox's, and the other 1 is
Phillips. Any help would be -greatly- appreciated!

Thanks ahead of time!

David,

This approach presumes you have a range of dates in which there are failures, and you want
that extrapolated to what would be expected in a full year, as a fraction of the total TV
sets. So if 3 sets failed in 4 months, then 9 sets would be presumed to fail in 12 months,
and the result would be 9/56, or 0.16074 (16%). If that isn't what you want, please be
clear on your requirements.

D9 must contain the end date of the period in which the failures occured, e.g.: 4/30/08).
You could use =max(A2:A5000) to pick up the latest date if you wanted to. Adjust A5000 for
the bottom of your list

=D10*(366/(D9-DATEVALUE("12/31/07")))/D11

The 12/31/07 is for the beginning of 2008. This formula uses 366 because 2008 is a leap
year.

Each time you work on this formula and press Enter, Excel will stupidly format the cell for
date, which is less than meaningless for this application. It does that to make solving
problems more difficult. Change the number formatting (Format - Cells - Number tab) to
general, percent, or something other than date.

To sum the failures, use something like this in D10
=counta(B3:B5000)

To sum failures for a particular brand, use something like (D10):
=COUNTIF(B3:B5000,"Magnavox")
--
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com
-----------------------------------------------------------------------
"David M" wrote in message
...
Could you give me a better layout. It seems I'm just either too dumb to put
it together, or simply am not selecting the right fields. Though your "C" and
"F" and etc is simple, I get an error. I'm using Excel 2007, btw.

Current Layout:
Date(A2) Brand (B2)
01/01/08 Magnavox (B3)etc
03/02/08 Phillips
04/25/08 Magnavox

Current Month: April (D9)
Total Failed this year: 3 (D10)
Total TVs: 56 (D11)
Rate of Failu ---(D12)
Percentage Failed: ---(D13)




"Earl Kiosterud" wrote:

David,

You don't say how your data is laid out, so I can only give you a general answer

C Count of televisions
F Failure count
P Period of failures, in days


= F * (365/P) / C

The above will give the fraction that would have failed in a year at the current rate.
For
a percentage, format for % or multiply by 100.

= F * (365/P) / C * 100

For the period, subtract the beginning and end dates:

= F * (365/(enddate - startdate) / C * 100

You need only replace F, enddate, startdate and C with the cells of your data.
--
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com
-----------------------------------------------------------------------
"David M" wrote in message
...
Here is the general concept.

I have 56 Televisions. The month is currently april and 3 of those 56 have
failed(quit, don't work). I am wanting to try and find a quick and easy
formula that gives me the rate of failure. I know it is probably something
simple, though it seems all brain power has left me on a friday.

56 Television
3 Quit
4 Months into the year
Televisions are 1997 or older
2 different kinds -- Magnavox and Phillips.

I have a spreadsheet all laid out, though I just can't seem to think of the
way to tie it all together. I would like to show the rate of failure between
the two brands as well. 2 of those 3 are Magnavox's, and the other 1 is
Phillips. Any help would be -greatly- appreciated!

Thanks ahead of time!