The Calculation Nodes

For this Driver Model there are going to be 2 Calculation nodes.

  • One to work out how much interest will be charged per month; and
  • One to work out how much of the loan will be left at the end of the month.

First we will set up the equation that will calculate how much interest will be charged per month.

  1. Drag a Calculation node onto the workspace and place it to the right of the other Calculation node.
  2. Rename this node Interest Charged.
  3. Link the Interest Decimal node to the Interest Charged node.
  4. Link the Prior Value node to the Interest Charged. Interest Charged Interest Charged
  5. Open the expression editor and enter in the following expression [Amount Left on Loan at the Start of the Month]*([Interest Decimal]/12).
    Note

    In the above expression we have divided the interest decimal by 12 because the total interest is charged at an annual rate. To get the monthly rate we have to divide the decimal by 12.

  6. Click Okay to save the expression.

For the final Calculation node we have to connect the following three nodes to find the total amount left on the loan at the end of the month.

  • Interest Charged;
  • Repayment Amount; and
  • Amount Left on the Loan at Start of Month.
  1. Drag the third Calculation node onto the workspace.
  2. Rename this node Amount left on Loan at End of Month.
  3. Connect the three nodes mentioned above to the third Calculation node.
  4. Enter the following expression into the expression editor [Amount Left on Loan at the Start of the Month]+[Interest Charged]-[Repayment Amount].
  5. Click Okay to save the expression.
  6. Finally connect the output of the Amount left on Loan at End of Month node to the input port on the Prior Node, this will complete the set up for our Prior Value node.
  7. Make sure Automatic Evaluation is turned on so you can see the immediate results. Completed Driver Model Completed Driver Model

Now that we have set up our Driver Model we can execute our scenario before going to the Research grid to investigate the influence of different inputs.