When you run a prioritization using a Monte Carlo simulation, the simulation generates a distribution of value outcomes. Optsee displays this distribution in a histogram in the Distribution Detail form. By examining these histograms, you can see how the distribution is skewed and whether it is smooth or discontinuous. This form is opened from the Distribution List Form.

Interpreting the Results:

When a histogram resulting from a simulation is created, Optsee® draws several lines to display the statistics associated with the distribution.

In the "Display Median, 90% and 10% Values" View, lines are drawn indicating the Less than 10%, median, and less than 90% probabilities. This can be interpreted as the median being the "most-likely" outcome with an 80% probability that the actual value is between the 10% and 90% lines. Therefore, there is a 10% chance that the value is below the 10% line and a 10% chance that the actual value is above the 90% line.

In the "Display Mean and Std. Deviation" View, lines are drawn indicating the mean (average) and the standard deviations.

These lines indicate the mean (average) value and the standard deviations (shown as the "sigma" symbol "σ") on either side of the mean. Assuming that the population is normally distributed (i.e. a bell shaped curve), the standard deviations can be interpreted as follows:

68.2% of the values fall between ±1σ
95.4% of the values fall between ±2σ
99.6% of the values fall between ±3σ
0.4% of the values are outside ±3σ

So, given this distribution, you can consider that

There is a 68.2% probability that the actual mean value is between ±1σ
There is a 95.4% probability that the actual mean value is between ±2σ
There is a 99.6% probability that the actual mean value is between ±3σ
There is a 0.4% probability that the actual mean value is outside ±3σ

These probabilities are important to keep in mind as you examine your results because often times the distribution curves have long tails with maximum and minimum values that are well outside ±3σ. While these are real values in the distribution, it's important to recognize that the probability of project value being at either end of these extremes is approximately less than 0.5%.

If a distribution is not normal (bell-shaped) or is discontinuous, then you need to consider that the probability of any given actual value is approximately proportional to the area of the bar corresponding to range of values that encompass the particular value.

Distribution Detail Form Buttons:

[Previous]: Click on this button to move to the previous distribution in the Distribution List Form. .

[Next]: Click on this button to move to the next distribution in the Distribution List Form.

[Close]: Click on this button to close the Distribution Detail form.