
1. Re: Does anyone know a way to aggregate new or impromptu data by weighted averaging?
Tracy Rodgers Sep 27, 2012 2:26 PM (in response to Stephen Bone)Hi Stephen,
So you mean you'd like a new weighted average for each new measure that you add to the data? If this is the case, you'll have to create a calculated field for each weighted average, unless you add it to your data.
Tracy

2. Re: Does anyone know a way to aggregate new or impromptu data by weighted averaging?
Mark Holtz Oct 4, 2012 11:19 AM (in response to Tracy Rodgers)Hi Stephen,
I'm not sure what method you're describing to get weighted average, so I'm not sure if this will be helpful to you, but we have a similar situation around some of our measures sometimes, and we have a very simple way of doing it.
Say for instance we have a % variance field for RevenuetoBudget.
Some clients may be way off budget, but they don't carry as much weight in terms of revenue...
Client C here is inflating the arithmetic average variance despite its lower relative weight.
4 clients:
Client Revenue Variance RevWeight WAvg Calc A $500,000 1.9% 0.476190 0.009047619 B $200,000 6.4% 0.190476 0.012190476 C $100,000 15.9% 0.095238 0.015142857 D $250,000 3.7% 0.238095 0.008809524 0.027571429 straight average: 5.13% avg weight by rev: 2.76% =SUMPRODUCT(B3:B6,C3:C6)/SUM(B3:B6) It's pretty easy to do a weighted average when you have the weighting field present and the weight is a proportion of the sum of the weight field. In Excel, you'd use SUMPRODUCT (value * weight field value) / SUM(weight field value)
In Tableau, you could make a simple calculated field for weighted average as:
SUM([Revenue]*[Variance]) / SUM([Revenue])
This would return the weighted average if you pull it into a view and should return the 2.76% in the grand total.