Parameters can be passed by reference. In effect if parameter value is changed in called analysis technique it's changes are reflected in the variable that was used to provide parameter's value in the calling analysis technique. You can mark parameter as reference in Analysis Technique Parameters window.
Example of passing variable as a reference (C#):
Function1(ref a); // note ref keyword
Example of passing variable as a reference (Visual Basic):
Function1(a)
See also Analysis Technique Parameters.