Rate for best performers as a subset of a larger group

[#1]

I am doing a line graph showing the rate for all facilites vs. the top 3 best (lowest rate) performers.  I can't seem to figure this out so i would appreicate some help.

Hospital	Quarter	Num	Denom
A1	q1	3	70
B2	q1	4	85
C3	q1	3	90
D4	q1	5	109
E5	q1	2	65

To show the rate for all facilities i simply have the expression =sum(<1 > Num)/sum(<1> Denom)

What i can't figure out is the expression for the combined rate of the best 3 facilities( with the lowest individual rate)

Thanks folks... I appreciate any help you can give me.!

[MayilVahanan]

Hi

     You can use rank() function to get  it.

[bgerchikov]

Hi,

Try expression below:

=IF(AGGR(RANK( sum(Num)/sum(Denom)), Drugs) <= 3, sum(Num)/sum(Denom))

Thanks!

[#4]

ok i follow what you are doing till you put in "Drugs"  I don't understand that it is not a field that i have available.

I do appreciate the attempt to help...  my goal is a line chart with two lines... one line is just the rate for all facilities and the other line is the rate for the top 3 best facilities.

Thanks,

[bgerchikov]

Please review attachment:

=IF(AGGR(RANK( sum(Num)/sum(Denom)), Hospital) <= 3, sum(Num)/sum(Denom))

Hope it helps.