Which object are you using (Assuming Pivot Table)? As suggested by Stefan you can use Above() function. Please provide the sample QVW file and expected result and one of us can provide you the solution.
Ill give you an example which will explain why its not appropirate. I have a table with two fields, Date and Net_VALUE. Using an input box the user will select two dates which will be the upper and lower bound. I basically want to calculate the % change in Net_VALUE between two coresponding dates using the upper and lower bounds.