What is it?
A run chart is a line graph of data plotted over time. By collecting and charting data over time, you can find trends or patterns in the process. Because they do not use control limits, run charts cannot tell you if a process is stable. However, they can show you how the process is running. The run chart can be a valuable tool at the beginning of a project, as it reveals important information about a process before you have collected enough data to create reliable control limits.
What does it look like?
Run charts show individual data points in chronological order.
When is it used?
Run charts are often used with baseline data at the beginning of a project. If you do not have enough data for control limits, SQCpack let you switch the control chart display to a run chart and switch back when you have enough data.
Use run charts when you can answer yes to these questions:
Getting the most
Run charts should be used as a quick test of system performance. Start ups and short runs in manufacturing settings often produce too little data for conventional control chart analysis, but are easily analyzed in a run chart. Inspection data generated in these situations should be plotted immediately on a run chart to enable quick diagnosis of system changes over time or to identify signs that the process has begun to stabilize.
Run charts are good way to illustrate and share information with other departments. They are often used to post sales figures for all to see. Patterns and trends are much easier to see on a run chart than in a matrix of rows and columns.
Because run charts can be easily constructed, they are especially useful for one-time analysis of historical data.