Hi,

Can someone have a look at the below formula and some ideas on how to
improve the arrays, I understand I should be using the offset and indirect to
find the exact range to improve performance, however not to sure where to
brgin with this.

=SUM(IF((DUDListData!$T$2:$T$65536=DUDListData!$Y$1)*(DUDListData!$U$2:$U$65536=Summary!$G$2)=1,1,0))/SUM(IF(DUDListData!$U$2:$U$65536=Summary!$G$2,1,0))

Many thanks John