Explanation:

- Random sampling: This technique involves choosing a random set of data or events to measure performance. It's cost-effective and less time-consuming, but it may not always represent the entire picture.

- Personal observation: Here, managers or supervisors directly observe the performance. This allows for immediate feedback and understanding, but can be subjective and time-intensive.

- Performance reports: These are written documents that track and analyze performance data over time. They offer comprehensive insights and allow for data-driven decisions, but may lack immediacy.

- All of the above: Each method offers valuable insights. Thus, a combination, tailored to specific needs and contexts, often yields the best results.