Learning Center

Counters and lag operators are accessory functions to help you building and managing Monte Carlo simulations models.

A counter is a function that returns an increasing value every time that spreadsheet is calculated. A calculation of the spreadsheet is fired when the users modified any cell value, when the user hit the “F9” key or when a new simulation is sampled. You can enter a counter by the “sCounter” function. The first argument of this function gives a number identification for the counter and the second sets counter step size.

A lag operator stores the value of one or more cells and displays it in the next simulation. Lag operators can be used in a chain, allowing that the values of past simulations are used during the current simulation. A lag operator is called using the “sLag” function. The first time that this function is called it returns the “#NUM!” value since it doesn’t have any value stored. Pressing F9 a few times the error value will soon disappear.

The spreadsheet below shows how to use counters and lags to generate a Monte Carlo simulation with antithetic scenarios.

A

B

C

D

E

F

1

 

 

 

 

 

 

2

Antithetic simulation example:

 

 

 

 

 

3

 

 

 

 

 

 

4

Simulation counter

3

=sCounter(1,1,,1)

 

 

 

5

Normal random

-1.22341

=sRAND_StandardNormal()

 

 

 

6

Antithetic normal random (lagged)

0.379419

=-sLag(B5)

 

 

 

7

 

 

 

 

 

 

8

 

 

 

 

 

 

To restart the counters and clear the lag operators, just click on the button .

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