Help Manual


Sigma Magic Help Version 17

Cause and Effect Diagram


A fishbone diagram (C & E Diagram) is a pictorial representation of different potential causes that may be the cause of a given problem. A fishbone diagram helps the team brainstorm and list all potential causes for a given problem and capture the team's perception of the most important causes.

This tool can be added to your active workbook by clicking on Project and then selecting Cause and Effect > C&E Diagram.


Click on the Analysis Setup button on the main menu or the task menu bar to open the menu options for this tool.


A sample screenshot of the setup menu is shown below.
CE Inputs
Problem: Enter a problem statement. The problem statement should briefly describe the problem for which you are creating the fishbone diagram. This information is entered at the head of the fish.
Major Categories: Specify the major categories for the fishbone diagram. The available options are:
2 CategoriesUpdate the Cause & Effect diagram to have only 2 categories. These categories will be initially named Category 1 and Category 2. You can rename these categories later. The remaining four major categories will be hidden from view.
4 CategoriesUpdate the Cause & Effect diagram to have only 4 categories. These categories will be initially named Category 1, Category 2, Category 3, and Category 4. You can rename these categories later. The remaining two major categories will be hidden from view.
6 CategoriesUpdate the Cause & Effect diagram to have only 4 categories. These categories will be initially named Category 1, Category 2, Category 3, Category 4, Category 5, and Category 6. You can rename these categories later. You can use this option when you have your category names and don't want to use the default ones.
ManufacturingThis will use the categories: Person, Material, Method, Equipment, Measurement, and Environment. This is the default option.
MarketingThis will use the categories: Product, Price, Positioning, Place, Promotion, and People
ServiceThis will use the categories: Surroundings, Suppliers, Systems, Skills, and Safety
WorksheetYou can specify your own categories in the textboxes. These category names are saved on the worksheet and can be directly edited on the worksheet as well.
Categories: Depending on your specific project needs, you can edit any of the text in the categories textboxes.
Tabs: Click on the tabs to move between different pages. The first tab is the problem tab, which describes the problem and the major categories. Depending on the categories you specify here, the titles for the remaining tabs will change.
View Example: Click on this button to open the example file. You can view the example to get an idea of how to fill out this tool, or you can use the example as a starting point and modify it to meet your project needs.
Help Button: Click on this button to view the help file for this topic.
Cancel Button: Click on this button to discard any changes and close this dialog box.
OK Button: Click on this button to save changes and compute the analysis results. The system will try to equispace the causes and add them to your fishbone diagram. If you want to delete a cause, enter a blank description for the cause, and this cause will be deleted from the worksheet.
For each of the categories, click on the tab for the appropriate category and specify the causes for that category. A sample screenshot of the dialog box is shown in the figure below. CE Diagram Inputs 2
Causes: Once you select the major categories, the next step is to identify the causes within each major category. You can identify the causes using brainstorming exercises with your cross-functional team members or other tools such as process maps, fault tree analysis, FMEA, etc. to identify the potential causes. List all the causes for each category here.
Constant Factor: If the cause you are confident that, if controlled, will improve the problem under consideration, then you can mark that potential cause as a Constant Factor (C). Select the first radio button for these types of causes. We can use a Standard Operating Procedure (SOP) to address these causes.
Experimental Factor: If you are not sure if this particular cause has an impact on your problem but feel that it could have an impact you can mark this cause as an Experimental Factor (X). You would need to do further experiments to determine the impact of this cause on your problem. Select the second radio button for these types of causes.
Uncontrollable Cause: If the cause you have identified is an uncontrollable cause for the problem statement you are working on, select the third radio button. A cause is marked as uncontrollable if this cause is not within the span of control of your team or if it is too expensive, time-consuming, or difficult to control this cause. Make sure you do sufficient investigation to mark a cause as non-controllable. Maybe there is something you or your team could do to address this cause. All causes marked as uncontrollable will be eliminated from further analysis. Select the third radio button for this type of cause.
When the tool is opened, the main menu at the top may change to a task-specific menu, as shown below. If this menu does not open, click on the F4 button or the small arrow at the bottom right portion of your menu group to open this menu bar. fishbone task menu To add a potential cause to the worksheet, click on the type of symbol you want to add and then click on the worksheet to specify the location where the symbol should be added. The software will connect the symbol to the closest major category. If the software does not connect the potential cause to the right category, you can manually detach and attach the possible cause to a different category. The following symbols can be selected:
  • Constant Cause - Used to add a constant factor (C). This is the normal potential cause that the team members feel impacts the problem statement. Note that this diagram is still the potential cause, and data have not yet validated the cause. Hence, the cause may or may not impact the problem statement, but the team feels that this cause may potentially impact the problem.
  • Experimental Cause - Used to add the likely cause to the C&E diagram. This is the cause that your team believes is important, but they are not sure if this is a real cause or not. Additional experimentation is required to understand this cause better. Of course, this is still based on the team members' perception and needs to be validated using facts and data.
  • Uncontrollable Cause - Used to add an uncontrollable cause to the C&E diagram. Note that a cause is uncontrollable if the team does not have the resources to address this cause or the cause is too expensive or difficult to address. Any items marked as an uncontrollable cause will probably not be carried forward, so make sure that you mark a cause as uncontrollable that is really beyond the scope of your team.


Click on Compute Outputs to update the output calculations. This will list the total number of causes identified in the Conclusion box. A sample screenshot of the worksheet is shown below.
Fishbone Diagram Example This worksheet does not perform any analysis except to list the total number of potential causes identified, the number of most likely causes identified by the team (if any), and the number of uncontrollable causes identified by the team (if any). The more potential causes your team has identified, the better. A sample message displayed to the user is shown below. Fishbone Outputs


Here are a few pointers regarding this analysis:
  • Since this is a standard Excel chart, you can use Excel's Insert Shapes to add other shapes to this picture if required.
  • Currently, Sigma Magic can only create level 1 causes. All causes are attached to the main categories. If you have further levels of breakdown (by using the five why analysis), you can choose to add to the bottom-most level of causes to your fishbone diagram.
  • Do not manually add the causes & arrows since the software uses a specific naming convention for the item. You can add new causes or edit existing causes using the Analysis Setup options or by clicking on the causes on the task menu bar.
  • You can add any number of causes to the worksheet, but the dialog box editor can only display ten causes for each branch.


The following examples are in the software's Examples folder.
  • Create a cause & effect (fishbone) diagram for lack of sales within a company. Brainstorm the various causes within your team and create the C&E diagram (Fishbone 1.xlsx)

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