The moving range is the difference between two successive data points. For a data set the moving range is a list of values. The moving range shows the stability of the data and is often presented in a moving range chart to more clearly illustrate this.
Subtract the second data point from the first data point and record this value. As an example take a data set of {1, 4, 4, 2, 7, 3}. Subtracting the second data point from the first gives us: 1-4 = -3.
Take the absolute value of the result. Continuing the example: abs(-3) = 3. Record the result as the first entry in a list.
Repeat step 1 and 2 for the rest of the data points starting by subtracting the third from the second. Again from the example data set, {1, 4, 4, 2, 7, 3} : {(1-4), (4-4), (4-2), (2-7), (7-3)} = {-3, 0, 2, -5, 4} = {3, 0, 2, 5, 4}. This list is the moving range for your data set.