sS.XLS An Inventory Control Simulator on a Microsoft Excel
Spreadsheet
by John O. McClain Links: [ Downloading
| Errors | Free Software | John McClain's Page ]
This workbook allows you to simulate an s,S inventory control system with random demands and random lead times. This is also known as the Min,Max system, or the Reorder Level, Order-up-to system. Whenever inventory position is s or lower, order a quantity sufficient to restore it to S.
Unlike most inventory control formulas, the simulation does not assume that replenishment orders are delivered in the same sequence in which they are placed. That is, orders are allowed to cross. The model assumes that lead times are iid (Independent from each other, and Identically Distributed). It makes the same assumption about the interval between demands.
"Instructions" are given on a sheet in the sS.xls file, and simple help is available in the boxes on the "Simulation" and “Graphs” worksheets.
Simulation results are stored on the “Data” worksheet, along with the details of the model from which the results were generated. This allows simple access to previously run models. Of course, all of Excel's functions and graphs may be used to summarize and analyze the results.
This is a very simple simulator, intended for teaching purposes. You are welcome to use it in any manner, and change it as you see fit. This model comes without any guarantee whatsoever, and is distributed free of charge.
Warning: This workbook contains macros, so Excel may give you a warning when you open it. If you disable the macros, the simulation will not run.
Downloading sS
sS.xls is about 0.6 megabytes in size. To download sS.exe, click here and follow the prompts.
If sS.xls
Doesn't Work:
Some users find that the buttons in sS.xls do not work. If this happens,
Microsoft Excel has automatically disabled the macros that make it run. To fix
this (or to make sure it does not happen) follow these steps:
1. Start Microsoft Excel.
2. On the Tools menu, point to Macro, and then click Security.
3. Click the Security Level tab.
4. Click Medium. Then click OK.
5. Exit from Excel.
"Medium Security" will cause your computer to warn you when an Excel File contains macros, giving you the chance to disable them if you do not trust the person who supplied the file.
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