# Control Chart

### carolyn celestin

## ..

A control chart for a random variable x is a plot of observed x values in time sequence order.

1. Find the mean and standard deviation of the x distribution by

(a) using past data from a period during which the process was "in control" or

(b) using specified "target" values for mean and standard deviation

2. create a graph in which the vertical axis represents x values and the horizontal axis represents time.

3. Draw a horizontal line at height and horizontal, dashed control-limit lines

4. Plot the variable x on the graph in time sequence order. Use line segments to connect the points in time sequence order.