The website for LegalMetrict (www.legalmetric.com/judgereport/calc.cgi) makes it appear easy for a law department litigator to calculate the present value of a lawsuit’s projected gain or loss. Online you can fill in the annual cost of money, the average cost of the lawsuit per month and its expected duration, as well as the expected recovery or loss. The math is easy, but the figures you enter are increasingly hard to pin down. How long will a lawsuit last? What will you end up paying or recovering?
The site helps with the sheer math. What might help with realism are some kind of confidence ranges.