# Multiple Simulation Runs

Simulation Master Tutorials > Multiple Simulation Runs

Simulation Master allows for multiple simulation runs consecutively.  This is useful when there are one or more discrete decision variables, and we want to simulate each value of the decision variables.

For this tutorial we will use the following model used to make a purchasing decision of a component used in a larger assembly.  The vendor has given quantity based price discounts.  However, the more quantity that is purchased, the larger the inventory carrying costs.

Each time inventory falls to zero, the quantity of the current value of the quantity decision variable will be purchased at the current price value.

The goal is to find the purchase quantity that results in the lowest total annual cost.

There are two decision variables located in cells B4 and B5.  One is for quantity purchased and the other for price/unit.  We will run four consecutive simulations, one for each price/quantity combination.

When multiple simulations are run, the first simulation uses the value in the first cell of each decision variable range.  The second simulation uses the value in the second cell, and so on.  In our example, the first simulation will use the values in cells D4 and E4.  The second simulation will use the values in cells D5 and E5.  This continues for the remaining cells.

To start the simulation, click the Run Simulation button on the ribbon.

Enter the simulation parameters as shown.  Note that in the Simulation Runs box, we enter 4.  Simulation Master will run four consecutive simulations of 25,000 iterations each.  Each simulation will use a different value for each decision variable as described earlier.

When the simulations are finished, the Simulation Results window will appear.  When the window first appears, the results of the first simulation run is shown.  To select a different simulation run, click the drop-down box in the upper left corner and select the desired simulation.

The results of the remaining three simulations are shown below.

The mean total costs from each simulation is:

Sim 1: 60,519
Sim 2: 59,226
Sim 3: 59,026
Sim 4: 59,476

The minimum total cost was found in simulation 3.  This corresponds to a quantity of 3000 and a price of \$9.60 per unit.