Looking for a Cusum Chart Template in Excel?

QI Macros has a ready-made Cusum template for you!

cusum chart template in Excel

Cumulative Sum Charts are Used to Detect Small Shifts in a Process

The Cusum Chart can detect process shifts more rapidly than the Individuals Moving Range (XmR) or XbarR Charts. If a trend develops, it's evidence that the process has shifted.

A Cusum Chart consists of the following:

A target which is either provided by you or calculated as the mean of your data.
Upper Cusum Limit and Lower Control Limit lines.
C+ and C- lines which represent the cumulative sum of deviations of successive sample means from a target. Use these lines to determine if your process is shifting.

Cusum Chart Template in QI Macros for Excel:

QI Macros add-in for Excel contains an easy to use Cusum Chart template. The template is pre-populated with sample data to show you how the template works. Just delete the sample data or type your data over the filled in cells.

To Create a Cusum Chart:

Input your Target value in cell A3.
Input labels in column B and chart title in cell C1.
Input data into columns C to G. Just use column C if your subgroup size is one. As you input data in columns C to G, the chart will populate to the right.
St Dev in cell A5 and k (slack) in cell A7 will also be calculated. k (slack) defines the amount of shift from the target you want to be able to detect. This is an estimated value, calculated at 1/2 of StDev, but can be changed.
Fast Initial Response (FIR) value defaults to 0. This feature can be used to set an initial "head start" value to improve detection of an out-of-control condition at the start of the chart. If the process is in control, this initial head start has little effect; if the process is out of control, a signal will be given faster with a non-zero value than with a zero value.
h is called the threshold value or decision interval. It determines how many StDev from the mean the Cusum Limits are set.

NOTE: Using h=4 or h=5 and k=.5 will generally provide a cusum that has good ARL properties (per Montgomery SPC 4th ed.)

Find the Cusum Chart template by clicking on the QI Macros menu > Control Chart Templates > Special (CUSUM, EWMA) > Cusum Chart:

Cusum Template Options in QI Macros

Cusum: Standard template and formulas.
Cusum Warning Limits: Adds warning limit lines to chart (like 2 sigma lines on a control chart).
Cusum 95-99 CI: Uses confidence intervals to calculate warning limits.
Cusum FIR Adjusted: Uses an adjusted formula for k (slack).