Every valuation model is based on a variety of assumptions about the future. And assumptions about the future by nature are uncertain. How will you account for the fact? How will you account for this uncertainty? You will account for this uncertainty by doing a sensitivity analysis. Sensitivity analysis is the process how evaluating how sensitive your valuation is for changes in assumptions.
Since the DCF valuation model relies on a large number of assumptions, which are the ones you will focus on? Using Crystal Ball or @Risk or a similar software enables you to do sensitivity analysis on many variables at a time. How do you pick the top four – if you are using a data table approach to sensitivity analysis?
This page answers the question: What variables would you do a sensitivity analysis on when valuing a company using the DCF method?