Please STOP the Red, Yellow, Green

in Measurement

by David M. Williams, Ph.D.

This is part of a series of blog posts on measurement for improvement. You can read them all here.

There is an epidemic spreading globally affecting leaders and their use and display of data. In a recent article in the ACHE HealthCare Executive publication, fellow improvement advisor Brandon Bennett and I make the case for leaders to stop using summary statistics displayed in tables with data color coded with red, yellow, and green. You can access the paper here and see why we advocate for data over time in Shewhart statistical process control (SPC) charts.

One of the main reasons behind our argument is to distinguish between what is random, common cause variation, and what is not and act accordingly. When leaders can’t tell, they often react to the difference between two points or the change in color. Here is a popular graphic I created comparing what leaders think they are doing based on the colors versus what they often actually do.

Figure 1. RAG Dashboards. What you think you are doing versus what you do.

A key learning for leaders is to look at data over time in a Shewhart SPC chart to see if it’s random, common cause variation. If it is, our action is on the system and processes. If it has attributable, special cause, you want to work with people at the point-of-service and with subject matter experts to figure out what’s going on. Color-coded summary data doesn’t support you to learn or take the right action. Just say no to traffic light dashboards.


Want to learn about measurement for improvement? Check out my favorite book by Lloyd Provost and Sandy Murray called The Health Care Data Guide: Learning from Data for Improvement. Not in health care? Don’t worry. It’s still the best reference for improvement data and measurement out there.

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