Which distribution is typically used for probabilistic estimates in project management?

The Beta distribution is often utilized for probabilistic estimates in project management due to its flexibility and ability to model variables that are bounded on either side (such as time estimates for project tasks). This distribution is particularly valuable when estimating task durations and resource requirements, as it can be shaped to reflect varying levels of uncertainty and can emphasize the most probable outcome while allowing for the possibility of both optimistic and pessimistic scenarios.

In project management, the Beta distribution is especially useful when using techniques like the Program Evaluation and Review Technique (PERT), which employs three estimates—optimistic, pessimistic, and most likely—to determine a weighted average. The shape and parameters of the Beta distribution can be adjusted to reflect the specifics of the project context, making it a versatile choice for modeling unpredictability.

Other distributions, while useful in their own right, do not provide the same level of adaptability in project management applications as the Beta distribution. For example, the Normal distribution assumes that outcomes are symmetric and does not as easily accommodate the scenarios often encountered in project estimates that may lean towards a more probabilistic mode.