CR 2008, I have an integer field, sales amount, which I'll sort on, and I want to group it so that 25% of the results constitute one group, the next 25% the second group, etc. for a total of four groups. If I create a formula using PthPercentile, i.e.:

if {salestable.salesamount} <= (pthpercentile(25, {salestable.salesamount}) then 1 else
if {salestable.salesamount} <= (pthpercentile(50, {salestable.salesamount}) then 2 else
if {salestable.salesamount} <= (pthpercentile(75, {salestable.salesamount}) then 3 else 4

it creates it OK, but says it can't be used in a group because it's figured at runtime. Does anyone have a solution I could use? This seems like it should be a fairly simple thing to do.