Weighted evenly question in regards to average...

[cvgreports]

Not to trying to sound dumb or anything like that, but what exactly does it mean to make sure my final numbers are weighted evenly? Say my average for the year is 1:15 minutes on After Call Work, what would the weighted number be?

 

[Andrew Fergus]

Hi

If you are referring to weighted averages, then if the 'final numbers are to be weighted evenly' then this means each item contributing to the overall average has the same 'weighting' or base - a circular definition I know, but a normal average of all data points is, by definition, evenly weighted.

If the average was weighted towards the more recent items or data points, then they would have more impact on the average than the older items in the sample. This is achived by giving the later data points a 'weighting' greater than 1 but the older items a weighting of 1. If there are 100 data points and you give each data point a weighting of 1 then it is evenly weighted - each data point contributes 1% towards the overall average. If however you gave the last 10 data points a weighting of 2 (instead of 1), then the last 10 items would contribute (10*2)/(90 + 10*2) = 20/110 = 18% of the overall average (instead of contributing 10/100 = 10% if they were each given a weighting of 1).

I probably haven't explained this very well but there is a useful article here that explains weighted averages using examples :
http://mathforum.org/library/drmath/view/52724.html

more here:
http://mathforum.org/library/drmath/sets/select/dm_weighted_ave.html

and for the techncially minded:
http://en.wikipedia.org/wiki/Weighted_mean

HTH, Andrew

 

[cvgreports]

thank you so much Andrew, very much appreciated! And thanks for the links for more info as well.