Create a distribution from a set of points on a curve | Vose Software

Create a distribution from a set of points on a curve

Situation

We have a set of co-ordinates that we wish to use to construct a distribution:

1. {x, f(x)} for a continuous distribution where f(x) is (or is proportional to) the probability density at value x;

2. {x, F(x)} a continuous distribution where F(x) is the cumulative probability (P(X<=x)) at value x; or

3. {x, p(x)} for a discrete distribution where p(x) is (or is proportional to) the probability of value x.

Uses

There are many uses of this technique. For example:

 

Application

We can use the same techniques as explained in Method 3 to create distributions from a set of points:

If the data set is of the form of {x, f(x)}, we can use the VoseRelative function in ModelRisk; 

If the data set is of the form {x, F(x)}, we can use the VoseCumulA (or VoseCumulD) function in ModelRisk; or

If the data set is of the form {x, p(x)}, we can use the VoseDiscrete function in ModelRisk.

The three functions have similar formats:

=VoseRelative(min,max,{x},{f(x)})

=VoseCumulA(min,max,{x},{F(x)})

=VoseDiscrete({x},{p(x)})

The {x} values must be in ascending order for the VoseRelative and VoseCumulA functions because they construct a distribution shape. For the VoseDiscrete function this is unnecessary because it is simply a list of values.

See Also

 

ModelRisk

Monte Carlo simulation in Excel. Learn more

Spreadsheet risk analysis modeling

Tamara

Adding risk and uncertainty to your project schedule. Learn more

Project risk analysis

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