Are you looking for a business improvement tool that is intuitive, simple to use, and visual in nature? Do you want to explore your internal business process and make sure you understand all of the inputs, outputs, and potential error states? 

If you are answering yes to these questions, then using input-process-output could be the perfect methodology for you. Let’s find out more. 

Overview: What is input-process-output (I-P-O)? 

Input-process-output (I-P-O) is a structured methodology for capturing and visualizing all of the inputs, outputs, and process steps that are required to transform inputs into outputs. It is often referred to, interchangeably, as an I-P-O model or an I-P-O diagram, both of which make reference to the intended visual nature of the method. 

A simple example is shown below from research in healthcare.

As the methodology is incredibly versatile, it is used across many industries and sectors with (inevitably) some modifications and adaptations. These can include, for example, the addition of feedback loops from output to input, in doing so creating models analogous to closed-loop control theory.

Typically, we would use I-P-O in the “define” stage of a Six Sigma DMAIC project and follow a specific method for generating the model. The steps are:

  1. Decide upon the process steps that will be in scope of the I-P-O model. Try to ensure the the scope is manageable with, ideally, less than 10 process steps defined.
  2. List all of the possible outputs, including potential error states.
  3. List all of the inputs to your process steps, using clear descriptive language.
  4. Create a visual I-P-O model.
  5. Check that the inputs are transformed to the outputs via the process steps as shown in the model. 

Often, it can be helpful to have the team that’s generating the I-P-O model complete a Gemba walk. Visiting the actual place of work and viewing the process in action can tease out some of the less obvious inputs and outputs and contributes to continuous improvement of the existing process steps.

2 benefits and 1 drawback of I-P-O 

Used correctly, the I-P-O model offers a simple, practical, and efficient way to analyse and document a transformation process. Let’s explore some benefits and drawbacks of I-P-O.

1. It’s visual and easy to explain

It’s often said that the best business improvement tools are simple to use, intuitive, and visual, and I-P-O ticks all three of these boxes. A sheet of paper, marker pen, and an enthusiastic team willing to contribute will get you a long way. It’s also versatile, suitable for use with the executive management group as well as the wider business improvement team.

2. It’s easy to execute

There is a clear and simple methodology to generate I-P-O models, and this helps you recognise and document all of the possible inputs, outputs, and error states. As it’s visual, it’s easy to update and change as the team explores many potential inputs and outputs.

3. It’s internally focused without regard for external customers or suppliers   

Developing I-P-O models is usually all about internal business processes, and we often hear this called micro-process-mapping. This typically means we do not consider our external suppliers and customers in the analysis. However, don’t worry, we have complimentary models such as SIPOC and COPIS that help us make sense of the bigger (macro) picture.

Why is I-P-O important to understand? 

For such a relatively simple mapping tool, it provides a really powerful insight into our internal business processes. Let’s dig a little deeper.

It helps with defining your key process input variables

Once we’ve documented and visualised our inputs and outputs, we can turn our attention to determining and controlling which inputs provide a significant impact on the output variation — these are known as our key process input variables

It’s aligned with Six Sigma and Lean principles 

In a classic Six Sigma and Lean project approach, we strive to reduce process variation and remove defects and waste. With I-P-O, we identify inputs, outputs, and error states from our processes so we can begin to explore and understand the Y(output) = f ((X) input) equation.

It’s the perfect springboard to create full process maps 

Once we have created I-P-O models, we have the perfect starting place for generating complete process maps. This could be moving on to value stream mapping, spaghetti maps, or one of many other types of process maps that are available.

An industry example of I-P-O 

A government agency with multiple departments was embarking upon a business transformation project to improve customer service times and efficiency. As part of the transformation project, a Six Sigma Black Belt who was assigned to the activity was requested to explore and document existing processes and prepare the teams for process improvement.

The Black Belt chose to create I-P-O models due to the ease of use and versatility of the approach. Each of the business departments designated a team to work on the I-P-O models and, alongside the Black Belt, defined the process scope, ensuring this was of manageable size. 

With the teams in place and scope defined the process outputs were brainstormed and captured visually using whiteboards. The corresponding inputs were added, and the I-P-O models checked for completeness.

Generating the I-P-O models highlighted a number of potential output error states that were subsequently investigated as part of the business transformation project and contributed to improved customer service times. As the models were captured visually on whiteboards, they were easily updated during the project and used to inform staff of their contribution towards continuous improvement.

3 best practices when thinking about I-P-O 

Like many process-driven mapping activities, there are some key things for us to consider when creating I-P-O models. Let’s look at three of these. 

1. Remember: It’s a team sport; don’t go it alone 

Even relatively simple processes have multiple inputs and outputs. Often we find that different team members have detailed knowledge of specific process inputs and outputs, and we should make good use of this collective knowledge.

2. Make sure the scope is achievable

Don’t be overly ambitious with the scope and try to include too many process steps for your I-P-O model. If you find yourself listing 10 or more process steps, it’s probably time to stop and re-evaluate.

3. Consider all of the inputs and outputs 

Be diligent, get all the team involved, and make sure there is no bias — we don’t want to just list the things we think should be inputs and outputs in an ideal world. In addition, we should consider and document all of the possible output error states.

Frequently Asked Questions (FAQ) about I-P-O

Is I-P-O related to SIPOC? 

It can be a logical next step to create a SIPOC model from an I-P-O model. With SIPOC, we consider both suppliers (S) and customers (C) in the analysis, the so-called wider or bigger picture. With I-P-O, we concentrate more on the internal business process.

Where do I start with an I-P-O model? 

Start by defining the processes that are in scope, making sure the scope is manageable. Then consider and document all of the possible outputs from the process steps before moving on to capture the inputs.

Do I need a software program to generate I-P-O models? 

Definitely not. You can start with paper, pen, and a pack of sticky notes. However, there are a number of free templates available for download that can help you and your team as you start to populate the I-P-O model.

A final thought on I-P-O

Ease of use and versatility are just two of the major plus points of developing I-P-O models for your internal business processes. Add in their highly visual nature, and this means you can easily engage your team on a journey to continuous improvement.

About the Author