Monte Carlo simulation is a complex statistical modeling method which can be useful in financial planning. The goal of Monte Carlo analysis is to apply statistical realities over multiple simulations and conclude how many of those iterations had a successful result. As I have said many times, financial planning is as much an art as is it a science. Unfortunately there are no absolutes or guarantees even with proper planning. Past performance is not an indicator of future results, so relying on historical averages can be misleading. Analysis is a tool, but only the proper use of the tool combined with skilled interpretation provides any value.