The symbol X-bar refers to which one of the following terms?

The symbol X-bar is commonly used in statistics to denote the sample average or mean of a set of data. It is a central concept in statistical analysis and is crucial for understanding how data behaves. The sample average is calculated by summing all the values in a sample and then dividing that sum by the number of values in the sample.

This measure provides insight into the general trend of the data, which is why it's often used in various statistical applications, including control charts and hypothesis testing. In quality management processes, such as those utilized in the USAF Green Belt practices, understanding the sample average helps identify variations and assess process performance.

The other options reflect different statistical concepts. For example, standard deviation measures the amount of variation or dispersion in a set of values, percentage represents a part of a whole expressed in hundredths, and range indicates the difference between the highest and lowest values in a dataset. Each of these measures serves a unique purpose, but the term associated with X-bar specifically refers to the sample average.