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Blocker Clustering

Blocker clustering is a relatively new technique for identifying identical blockers in your work process. It is an effective way to improve your workflow.


The 5 principles of Lean management give you the opportunity to identify value, create continuous workflow and identify waste activities. With their help, you can create a lean workflow and easily detect and eliminate problems.

However, getting rid of a problem is not enough. You need to find what causes it in order to protect your work process from recurring issues.

Among the most common reasons for recurring problems are the blockers ( things that obstruct a team from performing a certain task). However, very often, when a blocker is resolved the team just keeps working on the task and the blocker reason is soon forgotten. Until it appears again.

The more often a blocker appears the greater impact it has on the average cycle time. Therefore it is better to collect blockers with as many details as possible and analyze them.

There is a relatively new technique developed by Dr.Klaus Leopold (author of “Practical Kanban”) that addresses this exact topic. It is called blocker clustering. Let’s explore it.

The Blocker Clustering Technique

Before we start, we need to clarify that the blocker clustering technique can be applied best if your team uses a pull system such as Kanban. Implementing a system of this sort gives you the opportunity to visualize your workflow and collect valuable information about each task.

All teams using a Kanban board can acquire a clear overview of their tasks. If a blocker appears each team member can notice it.

However, as soon as the blocker is resolved the team forgets about it and keeps working on their routine tasks. This may not be a good practice, because the same blocker may appear again and again.

Instead, try to gather all the information for all blockers that occur in your workflow. Write the details on sticky notes and collect them. Then, analyze the information on a monthly basis for example.

task blockersKeep in mind that capturing the blocked time is the most important factor that will help you identify most impactful blockers.

Group the blockers

The first thing you need to do after you have collected a certain amount of blockers is to divide them into two major groups:

  • External blockers
  • Internal blockers

It is crucial to calculate the total blocked time for each group you formed, so you can prioritize. Total blocked time is the metric you can use in order to identify which blocker types are most critical.

After you divided the blockers by external and internal causes, you need to form smaller groups. These groups should consist of blockers with identical distinctive marks.

For example, missing information, waiting for review, waiting for test and etc. Afterward, you need to calculate the total blocked time for each sub-group, so you can prioritize the blockers.blockers clusteringWhen you determine the most impactful blockers, it is time to locate the root cause for each one and find solutions. You can apply different root cause analysis techniques such as the 5 whys.

This method will allow you to discover what is the real reason for a problem, by asking consecutive “why” questions as many times as needed.5-whys-exampleWhen you identify the root cause you can hold a brainstorming session with the team in order to find a solution. Make sure to inform all parties involved when you have the solution ready.

This way you will able to prevent your workflow from recurring blockers or at least decrease the blocked time significantly.

It is also important to experiment with different solutions if needed. Sometimes the first solution you apply may not work properly. So be prepared to test various ideas until you find the optimal one. After all, minimizing the negative effect of blockers will help you alleviate the bottlenecks in your workflow.

Structure the blockers

Keep in mind that it may cost more to fix a blocker than it costs to be delayed. Sometimes blockers just naturally appear in the system and trying to fix them at any price may be dangerous. Here is a simple example.

Imagine that your team needs to record a tutorial, but the process is blocked because they don’t have the right tools.

So you decide to build them a whole professional recording studio. You will spend a significant amount of money for something that will be used occasionally and will require a lot of time to get a return on the investment.

Last but not least, you can use a simple matrix in order to identify which blockers have the greatest impact and which ones you can solve easily. This will help you pick some easy wins and distribute your efforts evenly.






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In Summary

Blocker clustering is a simple and effective technique that will help you:

  • Identify impactful blockers in your workflow.
  • Eliminate recurring blockers or reduce blocked time.
  • Increase the throughput and decrease the average cycle time.

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