Hey everyone, welcome to this lecture what is an x bar s chart. Although x bar and our charts are widely used, it is occasionally desirable to estimate the process standard deviation directly, instead of using the range chart. This leads to control charts for x bar and s, where s is the sample standard deviation. x bar and S is used when the measurement is continuous, and the subgroup size is greater than eight. Let's look at this example. You are conducting a study on the pulse rate of nine patients who are on strict diets and exercise routines.

To monitor the mean and standard deviation of the pulse rate of your patients create an x bar s chart. You take a pulse rate reading every day for each patient for 20 days. In this example, you are required to measure the pulse rate patient's pulse rate is continuous data. There are nine selected patients. There's the subgroup size is greater than eight. Here, you will be required to perform an x bar s chart.

So, how to construct the x bar s chart. You will learn that in the next lecture.