MATHCAD for electronics circuit analysis usable for production testing
I may be wrong, but Mathcad is not "circuit aware".  That is, it cannot take a schematic, netlist, and BOM and do what you're asking, a WCA for example.

What you can do with Mathcad is to input the equations that define the various parameters that you're interested in, such a voltage error or gain error, give a range of values for the various things that contribute to those parameters (like resistance tolerance), and have it produce a range for the parameters you're interested in - the Monte Carlo analysis user287001 referred to.

Our power supply group uses Mathcad as part of their analysis for the switch mode power supplies (SMPSs) they design, to analyze things like over voltage and over current trip points, for instance.