Compute the upper range limit using the formula on page 60 or on page 137

Understanding Variation {Managing Chaos ' Formulas For Charts for Individual Values and Moving Ranges are: Use the individual values to compute the Average, X. This value will be the central line for the X-chart. Find the moving ranges and _ compute the Average Moving Range, mR . This value will be the central line for the vol? chart. To nd the Upper Natural Process Limit for the X-chart: multiply the Average Moving Range by 2.66 and add the product to the Average. UNPL =f+ (2.66 at $2) To nd the Lower Natural Process Limit for the X-chart: multiply the Average Moving Range by 2.66 and subtracr the product from the Average. LNPL =f(2.66 x "712) To nd the Upper Range Limit for the at]? chart: multiply the Average Moving Range by 3.27. URL = 3.27 x "E ' The multiplicative constants of 2.66 and 3.27 seen in the equations above are scaling factors needed to convert the Average Moving Range into the values you need to obtain the appropriate limits for each portion of the X1921? chart. 0 USCJl limits may be consuucted with as few as five or six values. ' The uncertainty in the computed limits decreases as the amount of data used to compute the limits increases. 60 Appendices XMR CHARTS USING THE AVERAGE MOVING RANGE ' Use the individual values to compute the Average, X. This value will be the central line for the X chart. ' Find the moving ranges and _ compute the Average Moving Range, mR . This value will be the central line For the m1? chart. ' To nd the Upper Natural Process Limit for the X chart: multiply the Average Moving Range by 2.66 and. add the product to the Average. UNPL =f+ (2.66 x :3?) ' To nd the Lower Natural Process Limit for the X chart: multiply the Average Moving Range by 2.66 and subtract the product from the Average. LNPL =f (2.66 x mR) To nd the Upper Range Limit for the m1? chart: multiply the Average Moving Range by 3.27. URL = 3.27 x JR The multiplicative constants of 2.66 and 3.27 seen in the equations above are the scaling facrors needed to convert the Average Moving Range so you can obtain the appropriate limits on each portion of the chart. 137