Squiggle is a minimalist programming language for probabilistic estimation. It's meant for intuitively-driven quantitative estimation instead of data analysis or data-driven statistical techniques.
Guesstimate is a spreadsheet tool that helps you model and forecast uncertain quantities. Guesstimate's interface is similar to other spreadsheet tools, such as Excel or Google Sheets. Each model is a grid of cells, and each cell can be filled with a name and value.
Rather than just recording what you think will happen, PredictionBook allows you to record just how sure you are that it will happen. You can distinguish between those things you think will probably occur, and those things you're really really sure will occur.
