Saad, Originally posted in cdnusers.org by lwang
Thanks for asking this.
Basically, measurements are according to the definitions. not such scientific algorithm behind there. You can find some definitions from CDSDOC-> PCB SI-> SigExploror User Guide-> Custom Measurement-> Measurement Expressions.
You also can contact Cadence education for the PCB SI training around you. Here is the link for North America.
Hope this helps,