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BACI Charts Help

BACI charts are used to judge how a change has impacted a process. It is usually used to judge the impact of a change on the same type of equipment or, at least, equipment that produces the same thing. For example, suppose we have three machines and want to make a change that will increase the value of an output characteristic. We make the change to Machine 1 first to see what impact the change has. This is the baseline data. Then we make the change for Machine 2 followed by Machine 3 and plot the results over time. The program gives you the option to calculate control limits for the baseline data if desired.


You have three machines making the same product. You want to see if a change will improve an output variable for each machine. You collect baseline data on Machine 1 and then make the change (on 3/30/2010 in data below). After you see the results on Machine 1, you make the change on Machine 2 (4/24/2010) and then on Machine 3 (5/17/2010). The data you collected are shown below.

BACI Chart Output

The BACI chart for the data in this example is shown below.

The BACI chart can be updated with new data. Select the “Update Charts” on the “Updating/Options” panel on the SPC for Excel Ribbon. Select the chart you want to update. All charts in the workbook are listed. You have select multiple charts at the same time to update.

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