![]() ![]() With the reference line selected, press CTRL+T to open up the Edit Reference Lines dialog. First add a reference line to your control chart by right clicking on your chart and selecting Add > Reference Lines…įill out the dialog as you please by entering a few values, and hit OK to add your reference line to the chart. When adding reference lines to a control chart, you can choose whether you want the data label to appear on the lower end or higher end of the line. I would like to close this post with a very minor but useful tip. The Editor Menu dynamically changes based on what you are currently selecting with Minitab.) Under Editor > Select Item, select "Symbols." If we had hidden the points from the bottom graph, we would have selected "Symbols 2."Īfter the symbols have been selected, press CTRL + T to go to the ‘Edit Symbols’ dialog window or simply to go Editor > Edit Symbols… Scenario 4: Setting Data Labels on Control Charts (Make sure you have your graph selected prior to doing this. Have we lost our symbols?įortunately, we have not. But what if we have a change of heart and want those symbols back? We right-click on different places on the graph, but all we see are options for “Edit Figure Region…”, “Edit Data Region”, or “Edit Connect Line…” Uh-oh. The symbols disappear from the top graph. On our Xbar-R chart, let's hide the symbols from the top graph (Xbar) by right-clicking on one of the symbols, and going to the Edit Symbols sub-menu…Ĭhoose "None" under "Custom" and select OK. Scenario 3: Hiding Symbols on Your Control Charts You could set this to be the default behavior under Tools > Options >Control Charts and Quality Tools > Other: This change can be made in the Xbar-R Options sub-menu, under the Display tab:Īfter checking this box and hitting OK a few times, your Xbar-R Chart will show the control limits for all stages. ![]() ![]() You'll notice that only the last stage’s control limits are displayed, but you really want the first stage's to be displayed as well. Let’s piggyback off of our first scenario and look at an Xbar-R chart with stages: Scenario 2: Showing Control Limits for Different Stages The resulting Xbar-R chart will set the standard deviation to 2 for the first stage, leaving the second stage unaffected. You’ll need to add an asterisk to represent the stage that is not affected by the historical estimate: You may be inclined to enter in 2 into the second box and hit OK, but that will set the standard deviation to 2 for both stages. You can enter historical estimates for the standard deviation under the Parameters tab under the Xbar-R Options sub-menu: For the second stage, you’ll let Minitab calculate the standard deviation. However, you want to use a historical standard deviation of 2 for the first stage, as opposed to letting Minitab calculate it for you. At each stage, Minitab Statistical Software recalculates the center line and control limits on the chart by default. Stages show how a process changes over specific time periods. Suppose you want to create an XBar-R Chart with stages. Scenario 1: Create a Control Chart with Stages For these scenarios, I used the XBar-R chart as my template, but you could easily apply them to many of the other control charts in Minitab. I wanted to share these potential scenarios with you in hopes that you will find them informative and useful. Hi everyone! Over the past month, I fielded some interesting customer calls regarding control chart creation and editing. ![]()
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