Mastering Cycle Time: Strategies for Reducing Variability

A cycle is a series of actions that recur in an unchanging order without discontinuity. To consider a cycle, we refer to the start of those actions till the next start. Thus, the cycle time is the duration from the beginning of one cycle to the start of the next.

In a previous article, I explained the difference between cycle time and lead time, highlighting that each concept offers different opportunities for improvement. Specifically, cycle time provides a leverage point for addressing variability.

Understanding Variability

Variability describes the degree to which process times fluctuate and deviate (from the norm). Technically, it measures how much process time differs from the average or expected duration. High variability creates unpredictability, making effective planning and scheduling a challenge.

Variability directly impacts clients in a delivery context, as it can lead to inconsistent or delayed deliveries. Therefore, observing and understanding the root causes of variability in a delivery cycle time is essential to ensure reliable and timely customer service. By identifying and addressing the sources of variability, companies can improve their delivery performance, ensure client satisfaction, and strengthen their competitive position in the market.

Typical Case

Here is an example. Let’s assume we observe clients entering a fast-food restaurant and ordering at the desk. We are interested in observing the cycle time, the duration between when a client arrives at the desk and when the next arrives at the same desk.

Therefore, we obtain the following graph showing the cycle time variability.

Variability root causes

Given the apparent variability in the cycle time, the next step is to understand why.

1. Clients are taking time to identify what they would like to order clearly. The boards or screens showing the menus could be more explicit. Let’s assume the root cause is a missing dry-run while creating those screens.
2. The employee at the desk needs to learn how to fill some orders, so he goes back to the team leader for more insights. For example, it might be because that employee did not get the required training.
3. The cooking equipment is dysfunctional, so the employee has to manipulate it several times to make it work for each order. It is because of the lack of maintenance or regular repair.

Therefore, from the situations above, we identify root causes we may tackle to reduce the ordering cycle time variability.

The 4M Framework to Managing Variability

We use the 4 M Framework to help identify variability’s root causes and the resulting actions. The 4Ms stand for Man, Machine, Method, and Material.

Men

• Are operators well-trained for their responsibilities?
• Did new hires get proper onboarding?
• Is the work environment satisfactory?

Machine

• Is the equipment functioning correctly?
• Are usage conditions within technical specifications?
• Is the maintenance performed adequately?

Method

• Does the method consistently meet customer needs?
• Is the method well-understood by everyone?
• Is it applied correctly? 
• Are we in the appropriate circumstances?
• Do we grasp the full context?

Materials

• Do components and inputs meet requirements?
• Did the supplier’s process change?
• Is the input data trustworthy?
• Do partners clearly understand the expected outputs?

You can see the “4M” as a category of variability root causes. Depending on your situation, the questions above help to know which category you are in. Thus, you determine the underlying root causes of the problem within each category. Then, you can easily propose actions to address the identified root causes.
Each category quickly leads to a type of action that reduces or eliminates variability.

Going back to our example above:

1. The missing dry run while creating the screens could be classified as “Material” because it is a missing input. Hence the required action to eliminate that source of variability.
2. Employees who don’t get the training could be classified as “Man.” Updating the onboarding process by including the required training will eliminate that cause of variability.
3. Dysfunctional cooking equipment could be classified as a “Machine,” especially in terms of maintenance. So, ensuring maintenance or regular repair will resolve the issue.

Variability introduces unpredictability, hindering effective planning and impacting customer satisfaction. Understanding cycle time is one way of observing and spotting the root causes of variability in a delivery process. The 4M Framework provides a structured approach for leveraging root causes of variability to define the appropriate action for improvement.