|Tool of the Week|
This week we’re talking about queuing theory. That is, the mathematics behind standing in line. More broadly speaking, queuing theory is used to understand how jobs are serviced in a work environment. Think about a bank or grocery store line – people show up with various needs, maybe browse around, a teller or cashier spends some amount of time processing the customer’s needs, and finally sends them on their way. That’s the same mechanism most of us experience in our jobs, regardless of what they are.
Why does this matter? At a high level, making improvements in any domain really means increasing some output (quantity, quality, revenue, etc.) or decreasing some input (time, costs, materials, effort, etc.). Queuing theory provides a framework for analyzing a system so a data backed decision can be made. The final state (goal state) being a smooth system that reliably delivers what it is supposed to.
Sticking with the bank example, if the average amount of time it takes to service a customer- greet them, provide the work they need done, and send them on their way – is 4 minutes, and there are 1,000 people who come to the bank each day, then there is a need for 4,000 minutes of labor to be available. That works out to roughly 67 hours of human labor time. If a shift is 7 hours of work time (no breaks included), than the bank needs to staff 10 people each day to meet the needs of customers. If there is a high degree of variability in the length of time a transaction takes, the amount of labor needed becomes harder to predict. A ten percent difference in average transaction time could mean needing 9-11 workers, all of whom want a paycheck. Too many staff and the business loses money. Too few staff and the business loses customers. Decreasing variability, then, is paramount to improving the performance of the whole system. Whether a bank, a manufacturing line, a restaurant, an accounting firm, design firm, or anything else, decreasing variability creates a smoother process, and a smooth process is the goal state. Without getting too far into the math weeds, the equation that matters most in queuing theory is Little’s Law. The law is simple math;
Wip = Throughput * Cycle Time
Which means that the number of jobs in a system (Work in process, Wip) is equal to the arrival rate (Throughput) multiplied by the time it takes to process the jobs (Cycle Time). So if average arrival rate in the bank is 100 people per hour, and it takes 4 minutes (.0667 hours) to service each customer, than the average number of people in the bank is (100* .0667) = 6.67. What’s profound about the law is that it applies to any system. From the paper in a printer reservoir, to customers in a bank, to the emails in your inbox, the same law describes each system. Still with me? It’s all being tied together soon.
No matter what type of work you do, Little’s Law shows us that to make an improvement in a system, we can only pull a few strings. We can decrease the cycle time by introducing more resources, we can decrease the arrival rate by limiting what enters the system, or we can pull both strings simultaneously. The goal being to decrease Wip.
Wip is not nearly as valuable as finished goods which why it’s best to reduce it. The same way standing in line is not good or ideal for a person, a product waiting in line is not ideal. Every job that exists has some arrival rate of “work” that needs to be “serviced.” To make improvements, Little’s Law sheds a light on what strings to pull to make those improvements.
This is an easy DIY experiment. Spend 60 minutes, 3-5x, measuring the number of “jobs” that enter your work system. Average those out to get the arrival rate (X/hour). Measure the amount of time a job spends being serviced a hand full of times to determine the average cycle time (Y hours). Multiply those two to get Wip. From there, it’s brainstorming to develop the solution that works for your business.
Adding additional resources has a certain cost, but provides a certain benefit. Reducing the number of services offered might seem like a strange idea, but it lowers the variability in customer requests, thus lowers cycle time. Next time you’re in a line, think about what could be done to make the line go faster. Then, apply the same ideas to your own business so your customers can skip the line.
What’s the smoothest process you know of? Let me know on Twitter: @Quinn_Hanson22
|Artist of the Week|
Carving marble statues is something I tend to attribute to ancient artists. With digital products consuming most of my attention in recent years, physical art has gotten far less attention that it deserves. This week I discovered Raffaele Monti, a 19th century artist who is famous for making marble look transparent. The below ph
otos get more mind blowing the more I think about them.
Trivia of the Week
This week’s trivia was inspired by a local trivia category from long ago. The idea is to guess the word being described. Hint, each answer is an animal as well as a verb.
1. To Suffer, endure, or undergo
2. To imitate, mimic
3. To stoop or bend suddenly
4. To stretch out one’s neck
5. To evade an obligation, duty or the like
6. To refuse to talk to reply
Tweet of the Week
A gentle reminder to stop and smell the rosey rosey roses.
Article of the Week
Written by serial author, Nassim Taleb, this week’s article is
Religion, Violence, Tolerance & Progress: Nothing to do with Theology. This short read is focused on how human behavior and values are not driven much by theology, but instead influenced by media, neighbors, and economics.
– For one can always find (thanks to the narrative fallacy) some stuff in a religion that confirms a given theory. Weber and the Weberians missed that the Industrial Revolution hit very early on northern France and Belgium (both extremely Catholic), while the Catholic South remained agricultural and socially conservative, so one can see with the naked eye that it cannot be about something proper to the theologies or the associated doctrines and practices. It is just that cultural norms are contagious within identities, and too mush so.
– People like to dress, act, even think in broad terms within the style of others members of their group, people they identify with — what we tend to loosely call “identity”. We will see further down that schisms and heresies look theological but, typically, in an inverse manner: group invent theological differences in order to separate.
– Dietary laws act as social barriers: those who eat together bind together. The onerous Jewish dietary laws helped create separate diasporas which allowed for survival, and prevented social dilution. Now consider the following: there is nothing particularly strong in Islam’s holy text against drinking alcohol, just a rather vague recommendation of avoidance of intoxication while facing the creator. But it made sense for social habits to interpret such a law as a firm interdict to avoid socialization with Christians and Zoroastrians in Baghdad when it was the capital of the Califate and Arabs were in the minority. It was the mentality that found theological backing, rather than the reverse.
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