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[Solved] How should I choose a probability distribution to represent uncertainty?

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(@leroysmith)
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Hi there, I am still learning Analytica and wondering which probability distribution I should pick for my model.  Is there documentation on recommended distributions for different applications?  Thanks for any help!

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(@krista)
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Take a look at Choosing a distribution page in the Analytica wiki.  For most purposes if the quantity is continuous, with or without bounds, it’s convenient to use the built-in function UncertainLMH(xlow, xmedian, xhigh) distribution. You specify 10th, 50th, and 90th percentiles for xlow, xmedian, and xhigh parameters. You can also specify plow as, for example 20%, in which case xlow and xhigh are the 20th and 80th percentiles. You can also set lower and/or upper bounds as lb and ub. It uses a simple but effective algorithm (from Hadlock & Bickel, or Tom Keelin) to create a smooth distribution between the specified values.  Hope this helps!  

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(@agy79a6q5vx0nbjjxy0vsixsg9b3)
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If you're talking about representing a subjective probability distribution, you probably can judge whether a crude first cut should be normal, lognormal, uniform, or triangular.  That's a lot better than just assuming normal distributions. One good possibility is sometimes what Krista Myers suggested.

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Download the free edition of Analytica

The free version of Analytica lets you create and edit models with up to 101 variables, which is pretty substantial since each variable can be a multidimensional array. It also lets you run larger modes in ‘browse mode.’ Learn more about the free edition.

While Analytica doesn’t run on macOS, it does work with Parallels or VMWare through Windows.


    Analytica Cubes Pattern

    Download the free edition of Analytica

    The free version of Analytica lets you create and edit models with up to 101 variables, which is pretty substantial since each variable can be a multidimensional array. It also lets you run larger modes in ‘browse mode.’ Learn more about the free edition.

    While Analytica doesn’t run on macOS, it does work with Parallels or VMWare through Windows.


      Analytica Cubes Pattern