average of group by

[Anonymous]

hello
I have a question about average with the group by
here is a sample from my data

root	sub	questions	scores
C	C.1	C.1.1	0
C	C.1	C.1.2	30
C	C.1	C.1.3	100
C	C.1	C.1.4	0
C	C.1	C.1.5	70
C	C.2	C.2.1	0
C	C.2	C.2.2	0
C	C.2	C.2.3	90
C	C.2	C.2.4	0
C	C.3	C.3.1	100
C	C.3	C.3.2	0
C	C.3	C.3.3	40
C	C.4	C.4.1	0
C	C.4	C.4.2	59
C	C.4	C.4.3	30
C	C.4	C.4.4	90
C	C.5	C.5.1	20
C	C.5	C.5.2	0

so I have the root C then the branches
I need to get an average of each sub by use chart drill down
as you can see here is the result I got bu used zoomcharts advanced donut visual 

it takes the average of the root based on overall branches but if I drill down the average of branches is correct but the root is not. 
here is an example for more explain
if I take the average of root C as here
(0+30+100+0+70+0+0+90+0+100+40+0+59+30+90+20+0)/18= 34.94
but if I take it by the group first the result is different
c.1=40
c.2=22.5
c.3=46.66
c.4=44.75
c.5=10
(c.1+c.2+c3+c.4+c.5)/5=32.7
and on the chart, C = 34.94 means it takes the average by overall
is there any chart or way to make it take the average for the group first?

[TeigeGao]

Hi @Anonymous ,

Actually, the average will be calculated based on the all number rather than the grouped one, why will you calculate the average of the grouped one directly?

Best Regards,

Teige

[Anonymous]

because I think this way is more accurate than the other
c.1=40
c.2=22.5
c.3=46.66
c.4=44.75
c.5=10
(c.1+c.2+c3+c.4+c.5)/5=32.7