weighted average.

[Npsays]

Hi !
I am stuck with how can we calculate weighted average. for e.g.

unit weight percentage error percentage
65% 1.49%
27% 0.84%
8% 0.75%

In the above 'unit weight' is allocated to 3 departments and besides the unit weight is the percentage of errors done by the unit. I need toi calculate the weighted error average for all 3 departments... any ideas pls ?

Thanks..says np.

 

[Oaktree]

Try =sumproduct(A2:A4,B2:B4) where A2 has your 65%.

 

[The Tamer]

Hi np.

Isn't it just an average of the averages?

I.e. ((1.49% + 0.84% + 0.75%) / 3)?

A = 1.03%

Or am I wrong?

 

[Oaktree]

Tamer:

No, that ignores the weighted part. 65% of the combined average should come from the 1.49%, so sumproduct is the way to go.

The "average of the averages" is 1.027%, but the weighted average is 1.255%

 

[The Tamer]

Thanks oaktree,

I make a point of getting an answer wrong every now and again to stop people from thinking I'm perfect and relying on me too much!

Generally, it works quite well.

 

[Npsays]

Hey ! thanks both of you ! and tamer.. i like your sense of humor