How can you use SPC analysis to identify the impact of process changes?

1 Define the process

The first step is to define the process that you want to analyze and improve. You need to identify the inputs, outputs, activities, and resources involved in the process, as well as the customers and stakeholders who are affected by it. You also need to define the scope and boundaries of the process, and the objectives and measures of success. A process map or flowchart can help you visualize and document the process.

3 Choose the SPC chart

The third step is to choose the appropriate SPC chart for your data and process. An SPC chart is a graphical tool that plots the data over time and shows the mean and control limits of the process. The control limits are calculated based on the natural variation of the process, and indicate the range of values that are expected from a stable and in-control process. There are different types of SPC charts, such as X-bar and R charts, p charts, or c charts, depending on the type and distribution of the data.

4 Plot the data and analyze the SPC chart

The fourth step is to plot the data on the SPC chart and analyze the results. You need to look for any patterns or trends that deviate from the mean or cross the control limits. These are called signals or special causes of variation, and indicate that there is something wrong or different in the process. You also need to look for any random fluctuations within the control limits. These are called noise or common causes of variation, and indicate that the process is stable and in-control.

5 Identify and implement the process changes

The fifth step is to identify and implement the process changes that are needed to improve the quality and performance of the process. You need to use root cause analysis, brainstorming, or other problem-solving techniques to find out why the signals or special causes of variation occurred, and what actions can be taken to eliminate or reduce them. You also need to consider the costs, benefits, and risks of the process changes, and plan how to communicate and execute them.

6 Monitor the results and update the SPC chart

The sixth and final step is to monitor the results and update the SPC chart after implementing the process changes. You need to collect new data and plot it on the same or a new SPC chart, and compare it with the previous data and chart. You need to check if the process changes have improved the mean, reduced the variation, or shifted the control limits of the process. You also need to check if the process is still stable and in-control, or if there are any new signals or special causes of variation.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?