What is an alternative name for X-R charts?

X-R charts are a specific type of control chart used in statistical quality control to monitor process variability over time. The 'X' in X-R charts represents the measurements of the process variable being monitored, while 'R' refers to the range of the sample. The use of these charts is primarily focused on continuous data and allows analysts to track the mean and variability of a process effectively.

The term "Variables Charts" is appropriate because it pertains specifically to charts that handle variable data, which is quantitative in nature and can assume an infinite number of values within a range. This characteristic differentiates it from attribute charts used for categorical data. By utilizing variable data, X-R charts can provide a more nuanced view of process performance, showcasing both the average and the dispersion of the data.

Thus, the term "Variables Charts" accurately captures the essence of X-R charts, as they are designed to monitor and control processes based on variable measurements rather than purely categorical outcomes.