EA - New probabilistic simulation tool by ProbabilityEnjoyer

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: New probabilistic simulation tool, published by ProbabilityEnjoyer on August 19, 2023 on The Effective Altruism Forum.Dagger (usedagger.com) is a new tool for calculations with uncertainty. It uses Monte Carlo simulation.There are two ways to specify your simulation model:Import an existing spreadsheetuse Probly, a Python dialect designed for probabilistic simulationℹ️ Each of the two links above has 4 interactive examples. You might want to start there.SpreadsheetExampleIn this 15-second video, we take a complex existing spreadsheet (100+ rows) from GiveWell and turn it into a Monte Carlo simulationThe sheet already gives us "optimistic/pessimistic" values, so it's as simple as adding one column to specify the distribution as (e.g.) uniform(Longer version of this video)FeaturesDependency graphIntuitive and mathematically rigorous sensitivity analysisOur sensitivity analysis uses Sobol' global sensitivity indices. The approach and the intuition behind it are explained in more detail here.ℹ️ You need to enable the sensitivity analysis under "Advanced options"Summary tableThis table exposes the structure of your model by showing the dependency graph as a tree. Similar to Workflowy, you can zoom to any variable, or expand/collapse.ProblyProbly feels very like Python, except that any number can also be a probability distribution:ExampleHere's a fuller example of the syntax and resulting output. It's part of a GiveWell CEA of iron and folic acid supplementation.Distribution supportProbly supports 9 probability distributions. Each can be constructed in multiple ways.For example, you can construct a normal distribution in 5 ways:This clickable table shows you everything that's supported, and includes example code:ℹ️ Shortcut: probly.dev redirects to usedagger.com/problyLimitationsThere are at the moment numerous limitations. A small selection of them:Probly:Doesn't support the Sobol' sensitivity analysisDoesn't show the dependency graphSpreadsheetThere is no UI in Dagger to edit the model. All changes must go via the spreadsheet.The spreadsheet must specify probability distributions in a specific format.All models are publicThanks for listening. To help us out with The Nonlinear Library or to learn more, please visit nonlinear.org