Business Process Modeling: Top-down or bottom-up processing?

Nov 25, 2014
Written by
David van Eck
David van Eck

Business Process Modeling: Top-down or bottom-up processing?

During Business Process Management trainings, people often ask me about the best modeling technique: How to model a process model? Where do I begin? Top-down or bottom-up process? Questions that many of you have asked yourselves when beginning to design a process model. In this blog I would like to take you along with me to the world of top-down or bottom-up modeling. Let me start by clarifying some frequently used terms. Then, I will share several personal experiences and my preferred method of working.

How to start modeling a process model?
Before elaborating on the complete process model in terms of work processes and process steps, I want to mention a couple of items the process designer should pay close attention to.

First, the designer should always determine what the aim of the process is, and which customer the process will be targeting. We determine the modeling goal and ask ourselves: Why are we making this process model? And Who is the customer?
Second, determine the process scope. Where does the process start and end? The start is the input of the process and is often called the ‘start trigger’. The end of the process is the output, or the result, and is referred to as the ‘end trigger’.
Next, the designer should determine which enablers the process has. The enablers are the actors that works with and in the process. For example roles or systems.
Finally, should any preconditions applicable to the process be taken into account? Keep in mind legislation or internal guidelines. The process model should adhere to each of these preconditions or guides.

How to start modeling

After having looked into the items above, the process model can be further worked out. We can distinguishes two modeling methods to design a model. The first modeling method is top-down, where we work from work process to process steps. The second modeling method is bottom-up, where we work from the process steps “upwards” by clustering the step in work processes. Both methods are describing how to design a process model.

Top-down process modeling
The top down method is often used by process designers who need a total and broad overview of the process model. In complex organizations this method will reduce the complexity of the process. The top-down modeling method we first defining the work process (number 2 in de figure top-down method) of the process model after having modeled the start and end-trigger (number 1 in the figure top-down method). As soon as we have modeled the highest level of the model, we can begin modeling a level below that. Each of the work processes in the different process steps is being modeled according to the related declaration and data carriers (number 3 in the figure top-down method). The other work processes will be developed in a similar manner. Next, we will determine which process steps need to be developed into a work instruction level. Finally, each process step will be assigned its role and possible system. As you can tell with this type of modeling, we start from the top with the work process and slowly work our way downwards towards the bottom level. To design with the top-down method we make a stratification within the model. In this way the process designer is able to structure the process model.

Top-down process model

Bottom-up process modeling
The bottom-up method is used by process designers that design a process model throughout their substantive knowledge. A process model can also be modeled according to the bottom-up method, by first defining each of the process steps in the model. Beginning with the start-trigger (number 1 in the figure bottom-up method), the designer will develop each of the process steps until the end-trigger is reached (number 2 in the figure bottom-up method). The process steps are further developed in a declaration and are saved on the relevant data carriers. Once each of the process steps between start and end-trigger have been completely developed we can begin introducing a structure within the model. We begin by grouping the process steps, which will further along again be grouped in a work process (number 3 in the figure bottom-up method). This modeling method is working from the bottom to upwards, starting with the grouping of the process steps and only then introducing a particular structure (grouping of the process steps into work processes at the highest level).

Bottom-up process model

My preferred method
My preference goes out to the bottom-up modeling method. I enjoy first determining and developing the content and then add structure in the process model. This method allows me to first determine the content with the experts that are doing the steps in this process and then fit it into a framework of work processes, easily letting me translate the content into a process model. In my experience the benefits of the bottom-up method are; it is recognizable for the enablers of the process; the process designer does not forget any details and it is not simplified. I identified two risk in the bottom-up method. When the whole process is modelled in detail I have to structure everything afterwards. This structuring of details afterward is a time expensive activity. And second, not all the details will have added value to the process model. I can imagine many of you prefer working out of the framework with a clear set of parameters. What matters is that each individual has an own preferred working style to go about modeling a process model. There is no best or worst preferred working style because the end result is still a process model. With this blog I want to create an awareness to be aware of your own preferred modeling style. I hope this has put into perspective the two modeling methods in drawing up a process model. Please refer to this blog to determine your preferred method and let me know why in particular you have opted for either of these methods.