A common and convenient way to express the uncertainty for a quantity is to estimate its 10th, 50th and 90th percentiles. You can then use Analytica’s UncertainLMH( ) function to fit a smooth probability distribution to these 10-50-90 values. Try it yourself. Without consulting the internet or other reference, consider the “official” coldest recorded air temperature in the US State of Hawaii, in Fahrenheit. Before reading on, write down your own 10-50-90 estimates.
I did the same exercise and came up with UncertainLMH(-15, -5, 10) shown on the left. UncertainLMH() also lets you set a lower bound (e.g. rainfall which can’t be negative) and /or upper bound, and change the probabilities — e.g. to 5-50-95th percentiles. See UncertainLMH distribution on the Analytica Wiki for details.