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  • Writer's pictureTilo Schwarz

Denise discovers the Cause Funnel


When Denise finally arrived home, she parked her car in the garage and took the elevator to the 4th floor. For a year, she had been living in this maisonette apartment in the city center, and she liked it. By the time she got through the door, she was too tired to cook. She grabbed a bowl of cereal, added some yogurt, sat down on the sofa, and turned on the TV.

An episode of a crime series had just started. This time it was about a murder case in a long-established, powerful industrial family. There were several suspects, but everyone seemed to have an alibi. Gradually, the investigators tried to establish the logical connections and encircled the perpetrator. Suddenly, Denise was wide awake. That’s it!, she thought.

She remembered the recent coaching cycles with Joe. He was currently working on reducing the quality issues after changeover on an automated screwing station in one of the assembly lines. His current obstacle was ‘damaged seals on the piston housing’.

The process ran like this:

First, the seals were manually placed on the housing by one of the operators. Second, the operator placed the lid on top and triggered the automatic station. The machine then put the screws into the holes of the lid and screwed it to the housing. Occasionally, seals were damaged in this process. Joe is currently struggling with finding out what caused the damage.

Denise had spent several coaching cycles to help Joe understand the situation better, but somehow, they seemed to spin their wheels.

Denise watched the investigators mark on a city map the location where the victim had been found and the whereabouts of the suspects. Where had everyone been seen last? Then they checked the times and compared them to the distances on the map. Determining the place and time of the event, Denise thought, that could help Mark too. She decided to try that the next day.


Wednesday, February 15, 7:45am, back to the office after an eureka moment


When she entered her office the next morning, Denise opened her learning notebook and quickly wrote down the idea she had had last night.


When struggling to understand the cause, analyze place and time of the occurrence.

Below that, Denise made a small sketch, thinking back to her training about Toyota where they used a funnel to illustrate the problem-solving process.

It's like a funnel, she thought. First it's about pinpointing the obstacle on the city map – where exactly does it happen, then determining the point in time - when it does happen - in order to observe the process more precisely at this point. This may reveal some patterns regarding time and place of the obstacle and could help to understand its cause.

I’ll call this the ‘Cause Funnel’, Denise thought. If the cause is unclear, go down the funnel. Denise smiled at the name for her new trick and closed her notebook.


She left her office and walked over to Joe’s storyboard to start their first coaching cycle of the day.

"Good morning Joe, we have arranged for a coaching cycle, is it suitable for you right now?"

Quickly they discussed target condition and current condition using their usual format of just mentioning the outcome metric and focus process metric using ‘Therefore’ and ‘Because’ as linking words.

Then they continued with reflecting on the last step. Joe was still working on the obstacle ‘damaged seals’. He had conducted a deeper analysis of the rework as his last step.

Denise asked, "And what did you learn from taking your last step?"

Joe responded, "I looked at the damaged and removed seals of the last two days. They definitely are scrap. We continue to have about 8% rework due to damaged seals.“

Denise went through the Improvement Kata Cycle in her mind. Although Joe had come up with a result for the last step, he had not gained deeper knowledge about the obstacle. His threshold of knowledge had not progressed. We are still at 2 o'clock on the Kata Cycle, Denise realized, the cause of the seal damage is unknown.

She decided not to move on to question three, but to follow up on the last step. "Joe, what exactly did you plan as your last step?"

"I wanted to take a close look at the damaged seals of the last two days, which were rebuilt by reworking them," Joe replied as if it seemed obvious.

Denise continued: "And what did you expect?" She used a deepening question on the last step.

Joe took a look at the experimenting record and began to read: "Last time I noted that we expected to know the exact cause of why the seals get damaged."

"And what did you learn from taking your last step regarding this expectation?" Denise followed up. She noticed that she was now using the original opening question of phase two again ‘what did you learn from taking your last step’ but with an addition that linked it to the expectation.

Joe replied defensively, "Well, I still do not know the cause. But I've already observed the process so much, and I am getting nowhere with this.“


Denise reflected on Joe’s reply. Joe has clearly reached his knowledge threshold. It is a bummer at this point in his kata practice that he still gets defensive when he reaches his threshold. Something I will have to think about later.

Denise kept thinking. At the threshold of knowledge, I would usually ask for the next step. But I have done this for the last two coaching cycles. This has led Joe to observe the process over and over, unfortunately, without gaining new insight.

Leaving Joe with yet another general process observation will not help and only cause more frustration. Now Joe needs my support in the methodical approach. This might be a test case for my crime-scene cause funnel, Denise realized.

Denise decided to try out her cause funnel by asking about the place: "Joe, where exactly does the problem occur?"

Joe reacted: "The defect in the seal is detected in the test stand when the tightness test is performed. But that is probably not the point where the seal is damaged. I think the seals could be already damaged the moment you insert them manually, or at the very latest when the lid is put on.“

Aha, a new threshold of knowledge, Denise realized. But we are a level deeper now at individual steps of the process.

She, therefore, now moved on to question 4. "Don't worry if you do not know where exactly the seals are damaged, Joe, what's your next step to find out?"

Joe responded, "I think it happens in the first two steps, but to really understand it, I will have to check every single process step. I think I will need to investigate 10 to 20 cases."

"Sounds great!," Denise nodded and asked, "how quickly can we go and see what we have learned from taking that step?"

They agreed on the next coaching cycle at the end of the shift the same day.

It was becoming increasingly clear to Denise that coaching went beyond asking the questions on the card. It was also becoming clear that the question card was a great reference. If she wandered too far away from that pattern, she would get in trouble.

The key was to deepen within the pattern by asking the right question at the right time. And it was not just random. There were rules of thumb, which Tilo called micro-skills, that helped to learn what to ask next. But it sure does require a lot of practice, Denise reflected, feeling exhausted. It seems harder for the coach than the improver. But I probably learn more and get more satisfaction from these sessions.

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