Help Manual

Contents






Sigma Magic Help Version 15

Multi-Vari Chart

Overview

Multi Vari charts can help identify the source of variation by plotting the data for several variables on a single chart. A multi-Vari chart is usually plotted for continuous data concerning three variables: positional variation, short-term variation, and long-term variation. By understanding where the variation is coming from, actions can be taken to reduce the total variation in the output. For example, you are trying to reduce the amount of variation coming from a piece of equipment. You collect data at different locations of the product, at different times during the data, and on different days of the week. This data can then be plotted on a Multi-Vari chart to determine if the most variation is coming from different positions on the product, from short-term variation, or long-term variation.

This template can be added to your active workbook by clicking on Graph and then selecting Multi Vari Chart.

Inputs

Click on Analysis Setup to open the menu options for this template. A sample screenshot of the menu is shown below.
inputs
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Chart Type: Specify the format of the chart. The following options are available:
OptionDescription
1 VariableCreate a Multi Vari chart with a single X variable.
2 VariablesCreate a Multi Vari chart with two X variables.
3 VariablesCreate a Multi Vari chart with three X variables.
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Primary Axis: Specify the variable to use for the primary axis. This is the horizontal axis at the bottom of the graph.
OptionDescription
PositionalUse the positional variable for the primary axis.
Short TermUse the short-term variable for the primary axis.
Long TermUse the long-term variable for the primary axis.
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Legend Axis: Specify the variable to use for the legend axis. This is the axis variable which is used to generate the legend axis. This option is available only if the number of plot variables is set to 2 or greater.
OptionDescription
PositionalUse the positional variable for the legend axis.
Short TermUse the short-term variable for the legend axis.
Long TermUse the long-term variable for the legend axis.
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Secondary Axis: Specify the variable to use for the secondary axis. This is the horizontal axis at the top of the graph. This option is available only if the number of variables is set to 3.
OptionDescription
PositionalUse the positional variable for the secondary axis.
Short TermUse the short-term variable for the secondary axis.
Long TermUse the long-term variable for the secondary axis.
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Help Button: Click on this button to open the help file for this topic.
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Cancel Button: Click on this button to discard any changes and close the dialog box.
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OK Button: Click on this button to save any changes and compute the analysis outputs if possible.

Data

If you click on the Data button, you will see the following dialog box. Here you can specify the data required for this analysis. Data
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Search Data: The available data displays all the columns of data that are available for analysis. You can use the search bar to filter this list and to speed up finding the right data to use for analysis. Enter a few characters in the search field and the software will filter and display the filtered data in the Available Data box.
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Available Data: The available data box contains the list of data available for analysis. If your workbook does not have any data in tabular format, this box will display "No Data Found". The information displayed in this box includes the row number, whether the data is Numeric (N) or Text (T), and the name of the column variable. Note that the software displays data from all the tables in the current workbook. Even though data within the same table have unique column names, columns across different tables can have similar names. Hence, it is important that you not only specify the column name but also the table name.
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Add or View Data: Click on this button either to add more data into your workbook for analysis or to view more details about the data listed in the available data box. When you click on this button, it opens up the Data Editor dialog box where you can import more data into your workbook, or you can switch from the list view to a table view to see the individual data values for each column.
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Required Data: The code for the required data specifies what data can be specified for that box. An example code is N: 2-4. If the code starts with an N, then you will need to select only numeric columns. If the code starts with a T, then you can select both numeric and text columns. The numbers to the right of the colon specify the min-max values. For example, if the min-max values are 2-4, then you need to select a minimum of 2 columns of data and a maximum of 4 columns of data in this box. If the minimum value is 0, then no data is required to be specified for this box.
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Select Button: Click on this button to select the data for analysis. Any data you select for the analysis is moved to the right. To select a column, click on the columns in the Available Databox to highlight them and then click on the Select Button. A second method to select the data is to double click on the columns in the list of Available Data. Finally, you can also drag and drop the columns you are interested in by holding down the select columns using your left mouse key and dragging and dropping them in one of the boxes on the right.
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Selected Data: If the right amount of data columns has been specified, the list box header will be displayed in the black color. If sufficient data has not been specified, then the list box header will be displayed in the red color. Note that you can double-click on any of the columns in this box to remove them from the box.
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View Selection: Click on this button to view the data you have specified for this analysis. The data can be viewed either in a tablular format or in a graphical summary.

Charts

If you click on the Charts button, you will see the following dialog box. Charts
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Title: The system will automatically pick a title for your chart. However, if you would like to override that with your own title you can specify a title for your chart here. Note that this input is optional.
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Sub Title: The system will automatically pick a subtitle for your chart. However, if you would like to override that with your own subtitle you can specify a subtitle for your chart here. Note that this input is optional.
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X Label: The system will automatically pick a label for the x-axis. However, if you would like to override that with your own label for the x-axis you can specify a different label here. Note that this input is optional.
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Y Label: The system will automatically pick a label for the y-axis. However, if you would like to override that with your own label for the y-axis you can specify a different label here. Note that this input is optional.
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X Axis: The system will automatically pick a scale for the x-axis. However, if you would like to override that with your values for the x-axis, you can specify them here. The format for this input is to specify the minimum, increment, and maximum values separated by a semi-colon. For example, if you specify 10;20 then the minimum x-axis scale is set at 10 and the maximum x-axis scale is set at 20. If you specify 10;2;20, then, in addition to minimum and maximum values, the x-axis increment is set at 2. Note that this input is currently disabled and you will not be able to change this setting.
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Y Axis: The system will automatically pick a scale for the y-axis. However, if you would like to override that with your values for the y-axis, you can specify them here. The format for this input is to specify the minimum, increment, and maximum values separated by a semi-colon. For example, if you specify 10;20 then the minimum y-axis scale is set at 10 and the maximum y-axis scale is set at 20. If you specify 10;2;20, then, in addition to minimum and maximum values, the y-axis increment is set at 2. Note that this input is optional.
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Horizontal Lines: If you want to add a few extra horizontal reference lines on top of your chart you can specify the values here. The format for this input is numeric values separated by semi-colon. For example, if you specify 12;15 then two horizontal lines are plotted at Y = 12 and Y = 15 respectively. Note that this input is optional.
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Vertical Lines: If you want to add a few extra vertical reference lines on top of your chart you can specify the values here. The format for this input is numeric values separated by semi-colon. For example, if you specify 2;5 then two vertical lines are plotted at X = 2 and X = 5 respectively. Note that this input is optional.

Verify

If you click on the Verify button, the software will perform some checks on the data you have entered. A sample screenshot of the dialog box is shown in the figure below. Verify The objective of this analysis as well as any checks that are performed is listed in this dialog box. For example, the software may check if you have correctly specified the input options and entered the required data on the worksheet. The results of the analysis checks are listed on the right. If the checks are passed, then they are shown as a green-colored checkmark. If the verification checks fail, then they are shown as a red-colored cross. If the verification checks result in a warning, they are shown in the orange color exclamation mark and finally, any checks that are required to be performed by the user are shown as blue info icons.

Outputs

Click on Compute Outputs to update the output calculations. A sample screenshot of the worksheet is shown below. outputs
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Notes: The text output of the analysis is sent to the notes section. This section contains the number of data points, the number of factors, and the names of variables to plot the primary, legend, and secondary axis. The analysis results section contains a summary of the output, namely the minimum, mean, maximum values, and the range of the output data. The maximum amount of variation contributed by each of the input variables is shown. The conclusion section contains the summary of which variable contributes the most to the total variation.

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Graphs: The graphs section contains the Multi-Vari chart of the given data set. The individual data points are joined by the black line. If there are multiple values in the same setting, the graph plots the average of all the points. The black line corresponds to the averages of the data points corresponding to the legend axis. The red line joins the averages for each of the data points corresponding to the primary axis. The green line joins the averages for each of the data points corresponding to the secondary axis.

Notes

Here are a few pointers regarding this analysis:
  • You can use the standard Excel functions to format the graph. However, note that if you click on Compute Outputs again you may lose all the formatting that you have done to your graph.
  • If you have missing data points, the corresponding data point is not shown on the graph and these values are not used in the average computations.

Examples

Following examples can be found in the Examples folder.
  • Create a Multi-Vari chart for the data given in the following file. Determine which is the major contributor for spread or variation (Multi Vari Chart 1.xlsm).