Where Birds Don't Fly

Special cause variation, also known as assignable cause variation, refers to variation in a process that can be traced to specific, identifiable causes or factors. These causes are not part of the normal, expected variability that occurs in a process. Identifying special cause variation is a critical aspect of process improvement and quality control. It involves distinguishing between random or common cause variation and variation that can be attributed to specific factors.  Key characteristics and methods for identifying special cause variation are control charts, unusual data points, patterns in data, data clustering, data outside specification limits, outliers, sudden changes in inputs, observations from process operators, root cause analysis, and historical data comparison.  Statistical control charts are graphical tools used in statistical process control to monitor process performance over time. They typically have upper and lower control limits that represent the accept...

Special cause variation, also known as assignable cause variation, refers to the variation in a process or system that can be attributed to specific, identifiable factors or events that are not part of the inherent, normal variability of the process. In other words, special cause variation represents deviations from the expected or standard performance of a process that can be traced back to specific, often unusual, and non-random factors. Key characteristics of special cause variation include: Identifiability: Special causes are specific and identifiable. You can pinpoint the exact reason or event that caused the variation in the process. Unpredictability: Special cause variation is typically unpredictable and sporadic. It is not part of the regular pattern of variation that a process exhibits. Infrequent Occurrence: Special causes occur infrequently and are often considered exceptions or anomalies in the process. Isolation: When special cause variation is detected, the goal is to ide...