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

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Active Member
Joined: 5 months ago

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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Posts: 3
Joined: 10 months ago

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!  

Posts: 2
Active Member
Joined: 1 month ago

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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