Check cadence manuals for analog simulation environment.
You will find one in
$CDS_ROOT/doc/anasimhelp/anasimhelp.pdf
and for advanced manual
$CDS_ROOT/doc/anasimhelp/anasimhelp.pdf
I think if you know the basics of cadence simulation environment, then I think you should go for the advanced manual directly as it's has a chapter for statistical simulation.