What is an Interference Diagram?

The Interference Diagram (ID) is a relatively simple tool to help surface, value and sort out interferences, Undesirable Effects or obstacles usually described as “problems”. The ID found its place within the Theory of Constraints Logical Thinking toolbox, but “Unlike the other thinking tools the ID is not based on logic, but rather on intuition(1)”.

>Lisez un de mes articles similaire en français

How does it work?

Gathering a group of people au fait with issues and the processes involved, the Goal to be achieved is written in the center of a board or paper sheet.

Every participant is asked to list the interferences he/she encountered, which is anything hindering the system to achieve the Goal.

Interference Diagram as I understand it is not a brainstorming tool, rather a mind mapping tool. The difference is about looking things that happened rather than think that could happen. The purpose of the ID is to understand and focus on unsolved problems that keep the system from achieving its Goal. This is important for the next step which tries to evaluate the impact of each interference based on the experience and memory of the participants.

These interferences are listed and written around the Goal.

Each interference, unless unvalidated by participants, is valued for its impact on the Goal, e.g. how much does it impair the system achieving its Goal.

Time is a convenient unit as it is common to everyone and every activity. Time can be later converted in other units like number of widgets potentially lost (lost time / unit cycle time, for example).

Once the interferences valued, the list can be ordered from highest impact to least, showing a Pareto diagram and giving hints about interferences to cope with in priority, which commonsense says are the most impacting ones(2).

When to use the Interference Diagram?

Sproull and Nelson(3) describe two use cases: to exploit a known constraint and developing an overall strategy plan (Goal Tree) and implementation plan.

I found the ID convenient to overcome the lack of available data, for example when a machine has a low OEE but no data recording can break down the causes of poor OEE.

The ID is therefore a convenient tool in case of problems but few, messy data.

(1) For more information about ID (origins, usage, etc), see: http://focusandleverage.blogspot.fr/search?q=ID+diagram
(2) I have a slight reservation about focusing solely on a Pareto Head, find out why >here<
(3) Epiphanized: Integrating Theory of Constraints, Lean and Six Sigma (TLS), Bob Sproull & Bruce Nelson, North River Press, 2012

Bandeau_CH36If you liked this post, share it!
View Christian HOHMANN's profile on LinkedIn

Solve problems and improve with few, messy data

Tackle problems and improve when data are available and neatly displayed in a Pareto chart is the way everybody expect to go, but this is not so often the case.

How to start in case of greater number of issues but very few data (read recording of sorts) about the problems exist and this few is messy, incomplete and inaccurate?
How to do when collecting new data may take too long and can be deceiving.
How to do when quick action is required ?

>Lisez cet article en français

Measurement is the first improvement step I once wrote in another post, which is still true, but in some circumstances, it’s not possible to set up a dashboard and wait for the first KPIs to come in.
In such a case, one must adapt to the situation and accept it as it is. Available data is scarce, questionable and messy? Just assume the data available is relevant, and then…

1. Use what is handy

Some data may be available and reliable: Production management data is generally well captured and filed as it is connected to P&L. Other data sources may be accurate: invoices or shipment data, for example.
Check what is handy and can be used then go for correlation rather than causation. At this point one needs to find leverage points, not definitive answers.

2. Investigate

Ask people who are confronted with the problems. They may give precious indications about their occurrences, conditions, intensity, importance and so on. The best is to conduct an interview without preconceptions and without suggesting answers.

It may be necessary to rephrase and thoroughly check the understanding as the interviewees will use their own words and descriptions.
Ask for the hit parade of problems or “undesirable effects” and use the Interference Diagram.

It may be based on gut feeling and memories but if crosschecked, it may come close to a consensual result. Best is to draw the diagram with a group: people will kind of auto-correct each other, especially people who tend to exaggerate problems in order to get attention to “their” problems.
Again assume what people said is relevant, consider them as subject matter experts.

3. Take samples

Go see and observe, if possible and relevant: measure. The sample don’t have to be statistically meaningful, the objective is still to get a “good enough” picture. Yet too few samples may be biased and too easily criticized by objectors.
When looking at human activities, the work sampling method does fine. It is about tallying the gesture or occupation at the moment the eyes of the observer catch the scene in a prepared form. Tally sheets may do in many cases when looking for samples.

4. Prepare a database

I usually prepare an Excel spreadsheet with columns as data fields and lines as records. When significant amount of lines (e.g. data) are recorded, the analysis can begin with a pivot table.

More sophisticated solutions may be used as well, but time is usually scarce. Furthermore Excel is most often available and many people know enough about it to give a hand.

5. Analyse

Study the available data and look for trends, patterns and correlations. When possible, go check the assumptions and reality / likeliness of the findings and discard or confirm scenarios. Keep track of tests and proofs in order to let others scrutinize and assess the analysis.

6. Set up measurements and dashboard

While investigating and coping with few messy data, measurements, data recording and dashboards can be prepared. This is for later confirmation and more accurate analysis in a second step. Yet preparing it soon will yield more data for later use.

7. Test

At some point the analysis shows leverage points, sources of problems and hopefully helps to find root causes. It is then time to test the assumptions by putting in place solutions and countermeasures.

Each action that alleviates the situation and helps to reduce the complexity is welcome, as it shaves off the bundle.

>Related post: If at least two tell the same

Bandeau_CH38View Christian HOHMANN's profile on LinkedIn

Video interviews with Bill Dettmer: LTP training participant’s testimony

Erik Mano co-Director of Marco Tech and Philip Marris CEO of Marris Consulting discuss Bill Dettmer’s Logical Thinking Process.

Erik Mano describes how he became interested in The Logical Thinking Process (LTP): his ambition to improve the performance of his company. Discovering Eliyahu Goldratt’s business novel “The Goal” and the hidden thinking processes it this book, reading Bill Dettmer’s book “The Logical Thinking Process” and then participating in Bill’s 6 day training workshop, applying LTP to his company and finally developing the habit of using LTP as an everyday reflex.

He comments on: the “Goal Tree”, the “Current Reality Tree”, the visual aspect of “trees” to explain and convince people and the “Evaporating Cloud” conflict resolution tool.

A quote:

By identifying your goal and where you stand today, you see the gap and you can get everyone to agree on the gap. Just doing this means you have reached quite a good level in your organization.

Filmed in Paris in November 2014. Video production by Christian Hohmann. Erik Mano was a guest of Marris Consulting.

>Previous video >Next video

View Christian HOHMANN's profile on LinkedIn

Tales from the Pyramid – the Swiss cheese

TfP_swiss_cheeseSwiss cheese as most people imagine it is a holed one. The pyramid in this post looks much like a portion of Swiss cheese, with holes in its middle layer. These holes stand for rogue middle managers who don’t align to corporate objectives, resist change or passively sabotage improvement programs.

Their behavior have various backgrounds and reasons yet impair the dependent departments and/or organization-wide initiatives.

Not playing by the rules while being in charge of a department is like leaving holes in the organization.

They are expected to carry out or support projects but don’t. In most cases they resist change fearing to lose the prestige and advantages of their current position. This is usually the case with people having (unexpectedly?) reached a top position, given their background, career trail and competencies.

High potentials usually do not worry about changes and challenges, they’re ready or even longing for them..

In industry I often saw this with maintenance managers, once good techies or engineers, promoted because of their technical skills but poor managers.

While struggling with management chores, they gradually lost their keenness about technique. Younger newcomers with technical degrees are more up-to-date and eager to climb the promotion ladder.

For the outdated managers, survival is often granted by their long experience and withholding information and knowledge, faking their expertise. Few knowledge is usually captured in (IT) system and even basic standards are not set.

The same phenomenon can happen in any department*, letting the organization dependant upon very few people with the alleged** know-how and barely willing to change the situation.

*‘Holes’ and similar behaviors can be found in the lowest layer of the pyramid, either because of the people’s own attitude or because they must carry out orders from rogue managers. Fortunately, in the lowest layer such individuals generally have limited influence.

**Sometimes the know-how is nothing but a myth.

The Swiss cheese pyramid looks like the one with the ‘hole’, but in that case the hole is made by a consistent category of employees, while in this case, the cheese holes are as many individuals.

One big hole or many smaller ones lead to the same effect: the organization is weakened, dependant on few, most of the time not fully company-oriented people.

Compared to the BlessingWhite types of employees, I would say the holes are mostly made by ‘hamsters’ and ‘crash and burners’.

Mending the holes can be complicated, requires a mixture of psychology, training, coaching and if nothing helps, the ultimate replacement.

If you liked this post, share it!
View Christian HOHMANN's profile on LinkedIn

Video interviews with Bill Dettmer: Logical Thinking Process training

William Dettmer is senior partner with Goal Systems International and author of eight books and numerous articles about Theory of Constraints, Thinking Processes and more. Bill was guest of Marris Consulting in Paris, France, November 27 and 28th, 2014. During his stay, we interviewed Bill and had the pleasure to video tape and later edit the clips.

>Previous video: the ‘magic’ teaser

>Next Video: Training participant’s testimony

View Christian HOHMANN's profile on LinkedIn

Chromebook, the end of honeymoon

One and half year after purchasing my Samsung Chromebook model 303C12, the advantages I once saw faded away in front of growing frustration, ending the honeymoon.

Let’s be fair, my Chromebook did overall well for what I asked it for. I wanted it mainly for convenient writing, long battery life and low weight.

I purchased it 300 Euros in July 2013, at a time no laptop PC I remember could meet this price. The limits of the Chromebook and applications became soon apparent as I tested it, but sticking to my prime requirements, still found it was a nice piece of technology.

Over time though, the limitations grew annoying.

Processing power

From the beginning it was clear I could not ask my chromebook to be an assistant to view high quality pictures taken with my DSLR, the processor was not fit enough to handle smoothly typical 7Mb photos without making you wait an eternity.

Watching videos in streaming also quickly faces the limits, which is a pity as I found convenient to use the Chromebook as a wifi receiver for TV shows replay on the Web and connect it to a TV set via HDMI.

Knowing the challenge such a thing is for the Chromebook, I did it over and over again, sometimes with fair results, but mostly with frozen screens while it was buffering up. When this happens every twenty seconds, you’ll quit watching.

Google docs

Great when I discovered it, Google docs in conjunction with Google drive allowed me to share files and write on any device in the most different locations and situations. But over time, docs begun to suck, especially when magnifying a bit the display, the cursor did not match the actual cursor position and drove me crazy as soon as I typed something after the left half of the doc’s page.

Due to this erratic cursor behavior I lost precious time to correct all my typos and my temper altogether.

Another great feature I use and abuse is the right-click search or define function. Alas, for some reason the first attempt in any session causes the search to freeze all the page and after a quite long moment to return a kind of “service not available” message.

This is even more frustrating as after regaining control and retry, the search or define works usually well.

What also increased over time is the freezing of the page (probably while Google docs tries to save onto Google drive, what it does permanently). It happens more and more often, which reduces greatly the interest of what I once felt as convenient writing tool.

Google sheets and slides

Sheets and Slides are simplified versions of Excel and PowerPoint. Ok for small modifications or quick work on small files, but not serious when trying to work and share files for professional use. I was once in a situation I had only the Chromebook at client’s premises and I understood it was to remain the only time.

Google drive

I was happy to discover I could use my iPhone to keep writing on docs while commuting by bus, but here also, over time, the crashes multiplied, letting me write few sentences before Google docs suddenly closed. By chance, the last sentences were generally still there, but every restart caused a long waiting time while the phone tried to connect to Google drive.

Alternately to crashes, Google docs suddenly denied any typing because it lost the connection to drive. The latest surprising change with Google Drive was the impossibility to edit a file without installing Google docs, which was not necessary previously.

This has nothing to do with the Chromebook you may say. That’s right, but docs, drive and the terminal used are a system and the Chromebook heavily depends on the other components.


The Chromebook and apps work best where PCs do as well: in environment with good WiFi and gets quickly disappointing elsewhere.

Only advantage left is longer battery life, but what’s the use if no meaningful work can be done?

Given the PCs price drop, they regained advantage especially because serious software can be installed.

For me that’s the end of honeymoon. I bought myself an Asus F200M with touch screen, barely heavier than 1 kg.

I will keep going with the Chromebook as a commodity.

Bandeau_CH38 View Christian HOHMANN's profile on LinkedIn

Goal Tree: is it worth it?

Depending the methodology, building a Goal Tree requires some time and attention from top management. The one I am thinking of is typically a two to two and half day seminar (when led by an expert). Therefore the Chiefs often hesitate to invest this time as they are already overbooked and question the necessity of the exercise: is it really worth it?

Yes, it definitely is!

It is worth to invest the necessary time to re (state), refine of review the Goal, define the Critical Success Factors (CSFs) to achieve the Goal and at least the first layers of Necessary Conditions (NCs), to achieve the CSFs.

It is worth because such a Goal Tree remains valid even if top managers leave, because it is tied to business fundamentals and not to someone’s “strategy”. Much of what a Goal Tree describes will remain valid, even if people in charge change.

Yes it is worth to invest time to set the benchmarks (CSFs and NCs), as they will remain valid over a period of time, because they are business fundamentals. World expert and father of the Goal Tree Bill Dettmer uses to say “Goal Tree well built remains valid until the business environment changes or the way the organization is doing business changes significantly“. Furthermore, compared to actual performance, these benchmarks will help to define the roadmap for improvements.

With these elements, the subordinates will know onto what to align their improvement efforts and get tangible and measurable ROI instead of sprinkling “improvements” here and there with sole measurable parameter being the cost of efforts spent.

Yes it is worth the C-suite invest some of its time to provide subordinates a sound vision, a clear Goal and direction about how everyone in the organization can contribute achieving the Goal.

It is especially worth when compared with the time spent in useless meetings and daily firefighting. Firefighting makes feel important and active, but in reality it is more gesticulation than action.

Aligning people’s daily efforts on meaningful targets will solve some problems and reduce the need for firefighting.

Alas, many world-saving managers don’t like this kind of wise and humble posture. This is good for old men meditating atop remote mountains, not for business warriors they think they are.

Yes it is worth to invest some time to get a visual management tool to assess progress towards the organization’s Goal, foster, sponsor, realign and refuel improvement programs. It is worth if after building a Goal Tree, the Chiefs use it for periodical review and self assessment.

An additional latter post discusses the ‘is it worth’ question: Goal Tree Chronicles – from Goal to action plan in a couple of hours

Bandeau_CH36If you like this post, share it!

View Christian HOHMANN's profile on LinkedIn