Why do buses come in threes?

Last year I came across two interactive models that struck a chord with me. They asked and answered, and allowed me to interact with two questions I have spent way too much time thinking about.

Although to be fair that time has a direct correlation with how these two scenarios have impacted me personally.

I spent way too much time in London waiting for buses. You wait and wait, and then they all come at once. And while you wait, you think.black-and-white-person-woman-night

Ditto time in the car. If you have ever driven on a congested motorway, like the M25 orbital around London, then I am certain you have come to a complete stop … for no reason. And while you wait,  you think.


Here are the two models:

  1. Why do Buses Bunch?
  2. Gridlock vs. Bottlenecks

Both were created by Lewis Lehe  on the Setosa blog and discovered by me in this article on the Flowing Data blog.

Models like this give me goosebumps.

They illustrate a difficult to explain and understand concept clearly. The interactive aspect of it makes it better. You can play and figure it out for yourself. Experience the behavior without having to live it.

This is why I like models and why I frequently use models at work.

The majority of models I create are diagrams. I’ll discuss diagrams at length over time. They are my go-to medium for discussions. Show me a whiteboard …

But I learnt to use Excel for this modeling from Alfred Mo a colleague of mine from my time Bank of America Merrill Lynch (BAML) in London. Alfred was the master of the Excel model. We created many Excel models to understand revaluations, cash-flows, and reversing journals (I was supporting Oracle Financials at the time) across a complex and effective architecture.

I took what I learnt at BAML and applied it at ICAP in London. The specific example that springs immediately to mind relates to a project to implement a new reporting tool for the Management Accountants.

This would be their primary reporting application. Their baby. This was the tool they cared about the most. It had to be right.

But it also had to be a few things to a few different people. It had to be one thing globally, and another in the regions.

The main challenge was allowing the teams to see local country numbers reported in a common reporting currency and converted in line with the accounting policies.

I had to understand what had been done previously. Pick through the language and terms used. Mix it in with what I already knew about the process from other roles at other companies, and add a dash of ‘what I knew from the Oracle way’.

To say it was confusing to everyone is an understatement. Everyone understood it differently and it was my role to document that and communicate it with the Devs.

I turned to Excel.

I created a model that allowed me to show how numbers in the Balance Sheet and P&L’s would be converted. I could demonstrate how those numbers would differ from the statutory account view. I could show what would happen over a year-end. I could help get an idea of the size of the database.

All from one model.

It was not easy to create. But learning from Alfred I worked something out. It had the desired effect. We found that common understanding of what was required.

And then I could share this working model with the  Development Team Lead, Ammar Yasir. He was then able to interpret that design a technical solution.

It worked.

It isn’t just that we had a solution. As you model the scenarios you learn more. You identify issues to be resolved.

You understand better.

Models help us think clearly. They help us design, strategise and decide.

Models give us the conditions under which things happen. They tie us to a mast of logic and that help us work out what is useful to us.

Models help us understand why, and they make us humble.

What have models have you created or used recently?

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One thought on “Why do buses come in threes?

  1. Pingback: Out of Fear of Embarrassment – Playing with Perceptions

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