Use factorsto determine the most probable outcome of already ongoing projects in your portfolio, and use it to simulate costs and benefits in proposed investments.
Simply enter the relevant factors and your initial estimates, and let factors generate multiple scenarios. Since each scenario is just as likely as any other, based on the same estimates, you need to analyse the whole set. factors shows you all scenarios in graphs, and let you select the subsets you are interested in.
Furthermore, factorscalculates which estimates contribute the most to the uncertainty. Use this information to prioritise which measurements to make in order to increase the precision of your estimates and reduce uncertainty.
Not only will you save hours by not having to enter mile-long complex formulas into a spreadsheet - and manually set up the graphs afterwards - you will also find it much easier to revisit your initial simulation throughout the project, and recalculate the probable outcome as conditions change.
You will also discover that your risk analysis makes much more sense as you use new or mitigated risks to adjust the simulation model in factors, and update the results.
factors is a stand-alone tool, not an add-in to Excel. And it is free!