Avg queue time = WIP / Throughput
Delivery rate = WIP / Lead Time
MeanResponseTime = MeanNumberInSystem / MeanThroughput
Avg Customers in system = Avg arrival rate * avg customer time in system
- Chris Young explains how he is using Little’s Law to estimate WIP a project’s delivery rate (5min video):
- Little's Law - The ONE thing you can do to improve process performance (6min video):
- Little's Law worked problem (6min video):
- The long-term average number of customers in a stable system L is equal to the long-term average effective arrival rate, λ, multiplied by the (Palm‑)average time a customer spends in the system, W; or expressed algebraically: L = λW.
- Although it looks intuitively reasonable, it is quite a remarkable result, as the relationship is "not influenced by the arrival process distribution, the service distribution, the service order, or practically anything else."