Säätökuvio

Säätökuvio, also known as a control chart, is a statistical process control tool used to monitor and control a process. It was developed by Walter A. Shewhart in the 1920s. The primary purpose of a control chart is to determine whether a process is in a state of statistical control. This means that the process is predictable and stable over time, with variations due to common causes rather than special causes.

A control chart typically consists of a centerline, which represents the average of the process, and upper and lower control limits. These limits are usually set at a certain number of standard deviations from the centerline. If the process is in control, most of the data points should fall within these limits. If a point falls outside the control limits, it indicates that the process may be out of control, and further investigation is needed.

There are several types of control charts, including the X-bar and R chart, the X-bar and S chart, and the individuals and moving range chart. Each type is suited to different types of data and process characteristics.

Control charts are widely used in various industries, including manufacturing, healthcare, and services, to improve process quality, reduce variability, and identify potential issues before they become significant problems. They are a fundamental tool in the field of quality control and process improvement.