Thursday, October 18, 2007

Little's Law

It strikes me that Little's Law [1] is a wonderful little equation that balances usefulness and simplicity. I wonder how many business cases and capacity evaluations I have made and evaluated that could have been done so much simpler! Two definitions:

a. For the business:

"The average number of customers in a stable system (over some time interval) is equal to their average arrival rate, multiplied by their average time in the system."

b. For the technical:

"The average number of objects in a queue is the product of the entry rate and the average holding time.'' [2]

[1] Little's Law (Wikipedia)

[2] Little's Law (Bell Labs)

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