Understanding Little’s Law
Little’s Law is a fundamental theorem in queueing theory that relates the average number of items in a system to the average arrival rate and the average time an item spends in the system.
Exam Question
Little’s Law states that:
(choose the best answer)
A. Average Cycle Time = Average Work in Progress / Average Throughput.
B. Average Throughput = Average Cycle Time * Average Work in Progress.
C. Average Work in Progress = Average Cycle Time / Average Throughput.
D. Average Throughput = Average Cycle Time / Average Work in Progress.
Correct Answer
A. Average Cycle Time = Average Work in Progress / Average Throughput.
Explanation
Correct Answer
A. Average Cycle Time = Average Work in Progress / Average Throughput:
Little’s Law is correctly expressed as Average Cycle Time = Average Work in Progress / Average Throughput. This formula states that the average time it takes to complete a task (Cycle Time) is equal to the average number of tasks in progress (Work in Progress) divided by the average rate at which tasks are completed (Throughput).
Why the Other Options Are Incorrect
B. Average Throughput = Average Cycle Time * Average Work in Progress:
This option incorrectly multiplies Cycle Time and Work in Progress. The correct relationship involves dividing Work in Progress by Throughput to find Cycle Time.
C. Average Work in Progress = Average Cycle Time / Average Throughput:
This option incorrectly inverts the relationship. According to Little’s Law, Work in Progress equals Throughput multiplied by Cycle Time, not divided.
D. Average Throughput = Average Cycle Time / Average Work in Progress:
This option incorrectly divides Cycle Time by Work in Progress to find Throughput. The correct relationship involves dividing Work in Progress by Cycle Time to find Throughput.
Importance of Little’s Law
- Predictability: Little’s Law provides a predictable relationship between key metrics in a workflow, helping teams understand and manage their processes better.
- Flow Optimization: By understanding the relationship between Cycle Time, Work in Progress, and Throughput, teams can make informed decisions to optimize flow and efficiency.
- Capacity Planning: Little’s Law helps teams plan their capacity by understanding how changes in Work in Progress affect Cycle Time and Throughput.
Effective Practices for Using Little’s Law
- Monitor Key Metrics: Regularly track Cycle Time, Work in Progress, and Throughput to ensure accurate application of Little’s Law.
- Adjust WIP Limits: Use the insights from Little’s Law to adjust WIP limits and optimize flow.
- Continuous Improvement: Continuously analyze and refine processes based on the relationships described by Little’s Law.
Relevance to the PSK I Exam
Understanding Little’s Law and its correct formulation is crucial for the PSK I exam. It demonstrates knowledge of key principles in flow management and their application in Kanban systems.
Key Takeaways
- Little’s Law states that Average Cycle Time = Average Work in Progress / Average Throughput.
- This relationship helps teams predict and optimize workflow by understanding the interplay between key metrics.
- Regular monitoring and adjustment of these metrics can lead to improved efficiency and capacity planning.
Conclusion
Little’s Law provides a fundamental understanding of the relationship between Cycle Time, Work in Progress, and Throughput. By correctly applying this law, teams can enhance their workflow management and efficiency. For more information on preparing for the PSK I exam, visit our Professional Kanban PSK I™ Exam Prep.
