Statistics

The X-bar and R charts are used to track the mean and variance of a process using samples obtained from the process. The method at specific periods. A subgroup is formed by the measurements of the samples at a specific time. Typically, an initial set of subgroups is used to approximate a process's mean and standard deviation. The standard chart for variable data, as well as the X-bar and R charts, aid in determining whether a process is reliable and predictable. The X-bar chart depicts how the mean or average changes over time, while the R chart depicts how the number of subgroups changes over time. It is also used to track the outcomes of process management theories.