How to Create Quality Control Charts in Excel

1. Distribute your data to revolve around a mean (average). Ensure your measurements are independent of each other. Create a subgroup for each data point and measurement number.
2. Add all your measurements in the subgroup and divide by your number of measurements. Calculate the mean of all the means; this will determine your over all mean. Determine the standard deviation of your data points by using this command: 'Standard deviation: =STDEV(data points).'
3. Tally the upper and lower control limits (UCL, LCL). Enter this formula: 'UCL = CL 3*S', 'LCL = CL -- 3*S.' This conveys 3 standard deviations above and below your mean. This will process your 1, 2 and 3 sigma lines. Draw a line at each deviation you've calculated. Diagram the subgroup means 'x-axis' counter to the 'y-axis.' Confirm that your points do not fall off any of your sigma lines. This can help you determine whether you data is 'in-control' or 'out-of-control.'