A run chart is a simple line graph that displays data points in chronological order, often to track changes or trends over time. Analysts commonly use them in quality improvement, healthcare, manufacturing, and other fields where monitoring performance over time is important. A run chart helps visualize whether a process is stable or changing and can highlight shifts, trends, or cycles in the data.
To create a run chart, you plot:
- Time or sequence order on the horizontal axis
- Measured values on the vertical axis
A median line is typically added to help assess patterns or shifts. Unlike bar charts or histograms, run charts preserve the order of the data, making them useful for detecting changes over time.
Run charts are like control charts but simpler. They do not include control limits or formal statistical rules. Instead, they rely on visual patterns around the median to identify possible signals of change.
Because of their simplicity, analysts of use run charts as a starting point when analyzing process behavior. They are easy to interpret and useful for identifying when a process might warrant closer investigation with more advanced tools like control charts.
Suppose a hospital tracks patient wait times in its emergency department each day for a month. By plotting these values on a run chart, administrators can see whether the process is improving, worsening, or remaining consistent. If several points fall above the median in a row, that may signal a shift in the process worth exploring further.
