Other Myths About Little's Law

This is post 8 of 9 in our Little's Law series.

In the previous blog post, we talked about the single biggest error people make when applying Little's Law. That's not to say there aren't others out there.

Thankfully, Prateek Singh and I recorded an episode of our Drunk Agile podcast to go over some of these other myths in more detail. While a large portion of what we talk about below is a rehash of the forecasting debacle, we also get into lesser-known problems like:

1. Using LL to set WIP Limits

2. "Proving" LL using Cumulative Flow Diagrams

3. All items need to be the same size

4. Cycle Times must be normally distributed

5. FIFO queuing is required

BTW, you will recall from a previous post where I quoted Little as saying, "...but it is quite surprising what we do not require. We have not mentioned how many servers there are, whether each server has its own queue or a single queue feeds all servers, what the service time distributions are, what the distribution of inter-arrival times is, or what is the order of service of items, etc." (1). If Little himself says that these are myths, who are we to disagree?

So grab your favourite whisky and enjoy!

References

1. Little, J. D. C., S. C. Graves. 2008. Little's Law. D. Chhajed, T. J. Lowe, eds. Building Intuition: Insights from Basic Operations Management Models and Principles. Springer Science + Business Media LLC, New York.

2. Drunk Agile YouTube channel https://www.youtube.com/@drunkagile4780

Explore all entries in this series

1. When an Equation Isn't Equal

2. A (Very) Brief History of Little's Law

3. The Two Faces of Little's Law

4. One Law. Two Equations

5. It's Always the Assumptions

6. The Most Important Metric of Little's Law Isn't In the Equation

7. How NOT to use Little's Law

8. Other Myths About Little's Law (this article)

9. Little's Law - Why You Should Care

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About Daniel Vacanti, Guest Writer

Daniel Vacanti is the author of the highly-praised books "When will it be done?" and "Actionable Agile Metrics for Predictability" and the original mind behind the ActionableAgile™️ Analytics Tool. Recently, he co-founded ProKanban.org, an inclusive community where everyone can learn about Professional Kanban, and he co-authored their Kanban Guide.

When he is not playing tennis in the Florida sunshine or whisky tasting in Scotland, Daniel can be found speaking on the international conference circuit, teaching classes, and creating amazing content for people like us.