Updated April 17, 2023
Introducing DMAIC Model
Six Sigma has had a roller coaster ride of popularity, but it is no denying that it has helped organizations make their processes more efficient. We’ve discussed the DMAIC model in Six Sigma and 20 things a Green Belt should know.
In a nutshell, Six Sigma is a culture or philosophy of quality control that permeates the entire organization. It is a data-driven approach to reduce and control defects, improving the process or product efficiency. Six Sigma is the level at which fewer than 3.4 defects per million opportunities/transactions exist.
The key question is: How do we go about implementing Six Sigma?
To implement the philosophy of the DMAIC model six sigma, we need a framework /roadmap to help us put our ideas to work. This roadmap is called DMAIC (Define, Measure, Analyze, Improve, Control) methodology. This framework converts the problem into something tangible to measure to arrive at a solution. This method can be most effective when any process or product does not meet customer expectations.
Examples To Implement
Let’s take a simple example to discuss how DMAIC can be used to implement Six Sigma, explaining each step in detail.
The Problem of the Late School Bus
Here is a problem faced by ABC Public School. There is a lot of confusion in the school. The class teachers have scheduled a meeting with the transport department to discuss an urgent problem.
Teachers: “Hello, Transport Department! For about six months now, we have noticed that the children traveling by school bus falling under Route 22 arrive late to class in the morning after the school bell rings. Many children miss a part of the first period.”
Transport department head: “We will look into the matter and revert with a solution.”
Route 22 is an important route covered by this school bus.
Teachers: “Fine. Let us inform the school principal as well. We can ask her for the solution.”
After listening to this problem, the principal decided to implement the Six Sigma methodology in the current transport process and appointed a Six Sigma Green Belt to tackle this problem.
The eager Green Belt has decided to adopt the DMAIC methodology. She has a team of Champions to assist her in the task.
The Define Phase
The Define phase is the first phase of the DMAIC roadmap. It is the base on which DMAIC rests. First, we need to identify the goal. Then, the Six Sigma Green Belt needs to determine the stakeholders for the process.
One can employ many Six Sigma tools to help in this phase. The most popular ones are:
- Project charter
- Process flowchart
- SIPOC diagram (Suppliers, Inputs, Process, Outputs, and Customers)
We’ve used the SIPOC diagram in our example. Let’s revisit our bus problem.
Three school staff previously trained as Six Sigma Champions have identified the team members. The customers are the class teachers, children, and parents. The entire current process of ‘School bus pick up’ is mapped. It starts with the driver coming to the bus depot and ends with the children entering the classroom.
The essential elements in this process are known as CTQs or Critical to Quality elements. What are the elements that make for a quality bus drive?
After a considerable amount of brainstorming with the customers, the six sigma team has identified the following factors:
- The children must be safe.
- The bus should reach on time.
- There should be no bullying on the bus.
- The ride should be smooth.
- There should be no overspeeding.
Among the above quality factors, the team has zeroed in on the second one, i.e., the bus should reach on time, because the other factors do not pose any problems currently.
This process is now the CTQ (Critical to Quality) element.
A SIPOC diagram showing the Suppliers, Inputs, Process, Outputs, and Customers will make the process very clear.
|School||Bus||A driver comes to the bus depot||Children reach school||Children|
|Bus suppliers||Driver||Takes charge of the allotted bus||Driver and monitor go home||Parents|
|Bus Monitor||Picks up monitor from school||Teachers|
|Children||Picks up the children from various stops.|
|Drops them at school|
|Children walk to class from drop off point|
After finishing our time analysis, we take random samples of 10 days during the month and record the delays.
Average delay = 60 minutes
Standard deviation = 35 minutes
The Measure Phase
In this phase, we attempt to answer these questions: Now that I know the problem, how do I measure it? Is the current system adequate for measuring the problem?
So let us quantify the problem, determine the data collection method, and measure current performance. We can use many DMAIC model tools in this phase, the common ones being:
- The Process Flowchart
- Data Collection plan
The keywords to be defined presently are Defect, Opportunity, and Unit. The Metrics will have to be arrived at.
In our study, the following definitions apply:
Defect: Any bus student delays in reaching the class.
Opportunity: Each bus ride to school.
Unit: Bus students’ arrival times
Throughout the process, there can be many points for data collection. The current system allows for data collection as follows:
Scanning his card, the driver records his arrival to take charge of his allotted bus from the bus stand. The time will be recorded at this stage. There is no data collection till the last step. In the previous step, the children scan their school cards to enter the school.
This method is inadequate as the Six Sigma team cannot collect data at each process point. Hence, the measurement is not complete. They have asked the school authorities to revise the data collection points by requesting a few system changes.
When the team implements the changes, they can determine when the driver takes charge of the bus. After which, the driver notes the time when he picks up the monitor. After that, the parents note down the time of the bus’s arrival and departure from their bus stop. Lastly, the children punch their entry cards.
So now, the data is collected at each step. A few random samples have also validated the data collection plan.
The Analyse Phase
The Analyze phase consists of statistical measurement of the collected data. We establish the correlation between the variables and the defect, and the significant contributors (KPIVs, which are Key Process Input Variables) are isolated. At the end of the stage, ascertain the function Y=f(x) relationship.
Various DMAIC model tools, like the Pareto diagram and Regression analysis, can be helpful. In our case, the Six Sigma team has decided to use the Root Cause Analysis tool.
The data is analyzed to identify the root cause of the delay. Record each minute process in detail. Eliminate non-value-added activities. A detailed study of the process flow would bring to light these activities.
Root Cause Analysis
|Process||Person involved||Time (minutes)|
|1||The driver punches his card||Driver||5|
|2||The supervisor allots the bus||Supervisor||5|
|3||Security gets the key||Security||5|
|4||The driver drives the bus to school||Driver||10|
|5||Picks up monitor||Monitor||5|
|6||Drive to stop A||Driver||20|
|7||Wait for the children and pick them up||Children||10|
|8||Drive to Stop B||Driver||15|
|9||Wait for the children and pick them up||Children||10|
|10||Reach the school||Driver||20|
|11||Children punch cards and enter the school||Children||5|
So the total time taken to reach school is 110 minutes. The highlighted parts are the “non-value added” activities. Eliminate these activities or streamline them to reduce travel time.
Some of the possible process improvements are:
- The keys to the bus can be readily available to the supervisor instead of the security guard wasting time getting them.
- The monitor can arrive at the bus depot directly instead of waiting at the school. That saves 10 minutes.
- In Step number 9, the driver waits 15 minutes instead of 5 minutes at the stop. They can aim to reduce that time by 10 minutes.
- Another potential improvement could be in Step 8 (travel from Stop A to B) and Step 10 (the trip from Stop B to school). An analysis of the causes of delays between these stops reveals areas of improvement that they can work upon.
- Step 8: Travel between Stop A and Stop B: There is a 10-minute traffic jam in 80% of the cases.
- Step 10: Travel between Stop B and school- One particular traffic light delays the travel by 5 minutes in 75% of the cases.
The Improve Phase
We can detect the actual KPIVs and their relationship with the defects in the Improve phase. The improvement ideas are finalized and implemented. The stakeholders should be willing to implement the new plan at this stage.
Our school bus project has entered a critical stage now. After a brainstorming session, they decided to take the following steps to improve the process.
- The supervisor will be in charge of the keys as well. It effectively saves 5 minutes of the driver’s time taking control of his bus.
- The Bus Monitor will board the bus at the bus depot itself. It saves 10 minutes of the driver’s time between the bus depot and the school.
- The delay in the drive from Stop A to Stop B happens due to a traffic jam on the main highway. It occurs 80% of the time. The driver has to find a solution and locate an alternative by-lane to avoid the traffic jam. It saves another 10 minutes of the journey.
- While traveling from Stop B to the school, a signal usually delays the bus by 5 minutes. Surprisingly no action was needed because the driver discovered that the additional time he got by applying the above measures meant that the traffic signal no longer troubled him. It was Green all the way! It was a bonus advantage to use the above measures.
- There was a delay of 5 minutes almost every day in Stop B due to one particular child arriving late. The teacher sent a message to the child’s parents. The driver must also wait at both stops only for a few minutes and leave afterward.
The school management has approved the implementation of these ideas with immediate effect.
The Control Phase
Once they implement the ideas, they become a requirement. It involves putting a system in place to ensure that the performance is controlled and measured. Standards and variances are defined and counted as part of a normal process.
The Six Sigma methodology has become part of the company’s philosophy.
The Six Sigma Green Belt job is nearly complete as she hands over the project to the new Process Owner (in our case, the Transport Department). These can be a part of good management practice.
The bus transport system works very efficiently now. The performance is monitored from time to time using Six Sigma.
There is another meeting in the school after the establishment of the new process.
Teachers: “We are pleased to report that the children are coming to class on time.
I can concentrate on my teaching, and the kids are happy.”
Transport department: “We are very thankful to the DMAIC model in the Six Sigma team for making our department very efficient.”
It is time to reward everyone involved in the project with a party and a bonus! That was yet another Six Sigma story with a happy ending.
This has been a guide to the DMAIC Model with Examples. Here we have discussed a brief overview of the different phases in the DMAIC Model. You can go through the following articles to learn more –