Which of the following metrics is NOT a commonly used KPI for measuring project performance?

The metric identified in the correct answer, staff turnover, is not typically considered a key performance indicator (KPI) for measuring project performance. Project performance KPIs usually focus on aspects directly related to the project's progress and outcomes.

Budge compliance measures how well the project adheres to its financial plan. Customer satisfaction reflects how well the project's outputs meet the needs of stakeholders or clients. Time taken to complete tasks is crucial for assessing whether project timelines are being met, which is critical for overall project success.

Staff turnover, while important for evaluating overall organizational health and workplace environment, does not specifically measure a project’s performance. It relates more to employee engagement and retention rather than the effectiveness or efficiency of a specific project. Thus, it is less relevant for assessing how well a project is being managed or executed compared to the other options.