Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Analyzing Variation With Run Charts
Key Points
-
Variation exists in all that we do.
-
Variation needs to be understood as it lays itself out over time.
-
Static displays of data using summary and descriptive statistics will not allow you to understand variation.
-
The Run Chart provides a starting point to understand variation in a process.
In the previous chapter, six of the milestones in the quality measurement journey (QMJ) were discussed. Particular attention was given to identifying measures, classifying them as outcome, process and balancing measures, the need for operational definitions, and, finally, data collection strategies. In this chapter, the next question is addressed: Now that you have data, what do you do with it? If you are genuinely committed to quality as a clinical and business strategy, then there is only one option: to understand the variation that lives in the data. This is best achieved by using statistical process control (SPC) methods and, in particular, the run chart and Shewhart control charts. In this chapter, the focus will be on the run chart. Chapter 28 (SPC charts chapter) addresses the Shewhart control charts.
What Is a Run Chart?
A run chart is a graphic display of data that:
- ▪
Makes the variation in a process visible in a way that static or descriptive statistics cannot do
- ▪
Confirms whether a change has led to improvement
- ▪
Verifies if the process improvement has been sustained over time
A run chart provides a running record of a process over time. Clinically it is like monitoring an intensive care unit (ICU) patient's vital signs moment by moment as they occur over time. The run chart, therefore, offers a dynamic display of the data and can be used on virtually any type of data (e.g., counts of events, percentages, volume, time, or money). Because run charts require no statistical calculations, which are required with Shewhart control charts, they can be made by hand or with software. A major aspect of using the run chart is that it can be easily understood by everyone on the team. Skill with making and interpreting run charts can be developed in less than an hour. The major drawback in using run charts, however, is that they can detect some but not all types of special causes. This last point will become more apparent in the following sections.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here
