Remove Distribution Extreme Values

Use this model object to remove extreme values returned by a distribution. Stat::Fit may recommend a distribution that looks like it will fit the data, but after review, it returns extreme values above or below what is possible in your system. Stat::Fit does not show possible extreme values, so additional steps are needed.

Why is this important? For example, suppose the average time for processing is 7 minutes, with a high value of 30 minutes. If the distribution returned an extreme value of 240 minutes (impossible in this system), the extreme time will cause havoc, tie up resources, and create huge delays. Some distributions create extreme values, such as the one portrayed above.

How do you know if the distribution returns extreme values?  By testing the distribution using the Verify Distribution Values model object. The Verify Distribution Values model samples a distribution thousands of times to show the possibility of return values. If other distributions don’t fit and the recommended distribution could work if the extreme values were removed, then this model object is exactly what you need. Note: every distribution should be tested.

The Remove Distribution Extreme Values model object isn’t used like most because it doesn’t remain in your model. Rather, it is first used as a standalone model to test the distribution, then by copying part of the logic into your model to replace the time value.

Where to Find the Model Object

The following model object can be found in the model objects directory:

• Misc \ Remove Distribution Extreme Values

If you can’t find the model object, select the Check for Updates option in the Model Objects menu.

Difficulty Level

• Ease of Use: Easy
• Ease of Modification: Easy

How to Use the Model Object

1. Open the Model Object: Locate the model object, Remove Distribution Extreme Values, and select the open button.
2. Define Values: Go to the action logic tab of Remove Distribution Extreme Values, and replace the distribution with the distribution you want to fix the extremes for.
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3. Define Minimum and Maximum Values: Within the same Action Logic window, define the minimum and maximum values you want to see for your distribution.
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4. Steps to Verify Distribution Values
   1. Simulate the model: It will run for 40 hours, sending over 140,000 entities through your distribution.
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   2. At the end of the simulation, click Yes to the prompt ‘Do you want to see the results?
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   3. Review the Variables tab to see minimum, maximum, and average values for the variable v_RecordToFile.
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   4. Click Export Variable icon in the toolbar to export variable data to Excel, choose the location where you wish to save the file, and click Save.
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5. Move Distribution to Your  Model
   1. Once you have verified that the distribution is providing correct values, copy/paste the “Remove Distribution Extreme Values” activity into your model.
   2. Click on the activity just copied, and open the Action Logic tab.
   3. Copy the action logic and paste it into the activity or route of your model.
   4. Update the time field on the activity or route move time to a_Time.
   5. Remove the copied activity from your model.

Controls Usage

Attributes:

1. a_Time: Attribute that will provide time value for the activity or the route in the model.

Variables:

1. v_RecordToFile: User input required. The return value of your distribution.