Probability Distributions

One of the two types of question in Foretold is the "distribution" type, made for estimating continuous distributions.

Currently a very similar distribution input method is used as with the application Guesstimate. All Guesstimate functions and distributions are supported.

Basic Input

The recommended way of entering most numbers is by using the basic input. Type

"10 to 30"

In order to submit a lognormal distribution with a 5th percentile at 10 and a 95th percentile at 30.

If the first number of these two is negative, then the distribution will be normal.

Function Input

If you would like to pick a specific distribution and it's corresponding parameters, you can use the function input. If you are entering a distribution, then you will need to refer to call a specific distribution. Here are a few common ones available. A longer list is here.

Distribution	Use Cases	Syntax
Beta	Estimations proportions or percentages, where the answer must be between 0 and 1.	=beta(α,β)
Normal	Most uncertain things, where the uncertainty is symmetric around the median.	=normal(μ,σ)
Lognormal	Similar to normal, but with a long tail on the right. Cannot be 0 or less.	=lognormal(μ,σ)
Uniform	A flat distribution, where everything inside is equally likely.	=uniform(a,b)
Multimodal	Weighted combination of distributions, giving multiple peaks.	=mm(d1, ..., [w1, ...])