# Thursday, December 5, 2013

How a humble bottle of tomato ketchup can teach us about flow, pull and push. 

Knowledge work tends to be Complex Adaptive work. That means as you try to solve a problem, the solution leads to a change in the problem you are trying to solve. It’s a bit quantum to be honest. You can either know what problem you’re trying to solve, or where you are in solving the problem, but you can’t know both until you’ve finished. 

What that means is Emergence happens. Emergence means that new work magically appears as you try to solve your complex adaptive work, so there is always (or close enough to always) more work to do than you think there is going to be. So if you plan 8 hours of work, you actually need 9 or 10 (or more) hours to finish it. So if you plan 100% utilisation based on the 8 hours, you are always going to be over capacity and needing to do say 2 hours extra per day to keep up. I suddenly have the U2 song “Running to stand still” playing in my head.  Time to start the metaphor, here we go.  

Lets imagine I have a plate of chips in front of me. I fancy a bit of tomato ketchup with my chips, but oh no! It’s the dreaded traditional glass ketchup bottle. 

I think we have all trained ourselves to solve this problem. Once upon a time when we were younger, more headstrong and foolhardy we would tip the bottle right up to 180º and, oh dear the ketchup has used the whole bottleneck, no ketchup can flow! Disaster!


What should I have done? Well the older, wiser, more thoughtful @KanbanDan knows that you have to tip the bottle to the optimum flow angle, whereby the ketchup almost, but not quite fills up the bottleneck. In order for flow to happen, the bottleneck cannot be 100% utilised.  

But what if I tip it too far? Well the adage about Push, Pull and Flow might just have the answer. 

Flow if you can, pull if you must.

(you may have noticed the absence of the word “push” in there, this is a deliberate omission)

You now have 2 options if you want ketchup for your chips while they are still hot:

1) The Push approach. 

You can start smacking the bottle on its bottom repeatedly until ketchup splatters out of the bottle. This tends to have consequences, which are exaggerated if you happen to be wearing white clothes or have a white table cloth.1

2) The Pull approach

Find yourself a knife which is narrower than the bottleneck, stick it in the bottle and pull some ketchup out onto your plate. If you pull effectively while maintaining the correct flow angle for the amount of ketchup remaining in the bottle, this will encourage flow to start. Flow if you can, pull if you must. 

Kanban is not a pull based system by design. Kanban is a flow based system, which suggests the use of pull where flow isn’t naturally occurring, to encourage flow through the bottlenecks in your system. 

Just like the ketchup bottle, if you plan to use your bottlenecked or constrained people or resource at 100% capacity, emergence will bite you and cause flow to fail. If that happens, sort out the flow angle (replan at less than 100% utilisation) and use Pull to get you out of the hole you just got yourself into. Pushing will just make things get really messy really quickly. 

"But why not just use a squeezy bottle Dan” I hear you ask?  

Well next time you get over capacity in your system, ask your most constrained person to stand up, wrap your arms around them, squeeze them hard and see how fast you end up being called into HR for a meeting. Just deserts for people who stretch metaphors too far ;-) 

 Merry Christmas Kanbanistas! 

Tags: Agile | Kanban | Lead Time

Thursday, December 5, 2013 6:01:04 PM (GMT Standard Time, UTC+00:00)  #