Which type of data is plotted on an X-bar and S Chart?

The X-bar and S Chart is specifically designed to monitor the mean and variability of continuous data, also referred to as variables data. This type of data is measurable and can take on any value within a given range. Examples of variables data include measurements such as length, weight, volume, and temperature, which are represented as numerical values.

When using the X-bar and S Chart, the 'X-bar' indicates the average of values taken from a sample, while 'S' represents the standard deviation, which measures the amount of variation or dispersion within the sample. By plotting this data over time, practitioners can detect shifts or trends in the process, allowing them to apply appropriate quality control measures.

In contrast, attribute data refers to categorical data that can only be classified into distinct categories, often represented as pass/fail or yes/no. Since the X-bar and S Chart requires quantitative measurements to assess process performance, it is not suitable for analyzing attribute data. Thus, the focus on continuous measurements in X-bar and S Charts firmly establishes its alignment with variables data.