|The Random Variables
add-in (ran_var.xla) performs computations associated
with probability distributions. When it is installed,
the OR_MM menu includes the menu items shown at the left.
Add Random Variable: With this command a dialog
is presented with sixteen named distributions, a discrete
user distribution and a general distribution. The add-in
creates a form holding distribution parameters. All the
other programs of the add-in use random variables defined
in this way.
Plot Random Variable:Up to three distributions
may be plotted using Excel graphics.
Simulate Random Variable: The add-in uses the
Monte Carlo method to simulate a function of one or more
random variables. The simulation reports sample moments
and a histogram of the simulated data.
Functions: The Function command creates
a form that defines several random variables and several
functions of the random variables.
Moments: This command is applicable to function
forms created by the Functions command. It uses
either enumeration of the sample space or simulation
to determine the mean and variance of the functions.
Relink Functions: This command is necessary
when opening a worksheet that contains user-defined functions
that were created on a different computer. The add-in
searches through all formula cells on the worksheet and
whenever a user-defined function is found, it is rewritten.
This works well if the function appears alone in a cell
or is the first term after the equal sign. When functions
appear deeper in an equation, the equation will be modified
erroneously. To guard against this result, place all
user-defined functions as the first term in an equation.