Which of the following techniques is NOT used to estimate activity duration?

Resource leveling is a technique primarily used to address resource allocation issues within a project schedule, rather than to estimate activity duration. This method involves adjusting the start and finish dates of tasks to resolve conflicts and ensure that resources are used efficiently without overloading them. While resource leveling can lead to changes in the timing of tasks, it does not inherently involve estimating how long the activities themselves will take to complete.

In contrast, the other techniques listed—expert judgment, analogous estimating, and parametric estimating—are directly focused on the process of estimating how long specific activities will require to finish. Expert judgment relies on the insights and experiences of individuals with subject matter expertise to gauge duration. Analogous estimating draws from historical data from similar projects to make predictions. Parametric estimating uses statistical relationships between historical data and other variables to estimate durations based on measurable parameters. Thus, these methods are all integral to the process of determining activity durations, differentiating them from resource leveling.