Help Manual

Contents






Sigma Magic Help Version 15

Dot Plot

Overview

Dot Plots can be used to compare different sets of data. Dot Plots are similar to Histograms except that data points are displayed separately instead of being boxed into groups. If you have less than 50 data points, it may be better to use Dot Plots instead of Histograms. Dot Plots can help visualize which data values occur the most often and give us an idea of the minimum and maximum values.

This tool can be added to your active workbook by clicking on Graph and then selecting Dot Plot.

Inputs

Click on Analysis Setup to open the menu options for this tool.

Setup

A sample screenshot of the setup menu is shown below.
inputs
1
Chart Type: Specify the format of the chart. This selection is not enabled since there is only one format available.
2
Bins: Specify the number of bins to use for the data plot. All the data that falls within a bin are grouped together and plotted under that bin. If you set this value as Auto, the system will pick a suitable bin size otherwise it will set the number of bins based on the value you set in this dialog box.
3
Multiple Plots: Specify how you want to plot the different groups.
OptionDescription
DifferentPlot each group of data points in a different plot
SamePlot all the groups of data points on the same plot with different colors.
4
Stack Groups: Specify if you want to add stack data from multiple groups on top of each other. This option is available only if you specify that all the groups should be plotted on the same chart.
5
Help Button: Click on this button to open the help file for this topic.
6
Cancel Button: Click on this button to discard any changes and close the dialog box.
7
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
1
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.
2
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.
3
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.
4
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.
5
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.
6
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.
7
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
1
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.
2
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.
3
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.
4
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.
5
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 optional.
6
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.
7
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.
8
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. Note that if there are multiple groups, then each group is plotted in a separate dot plot. By default, all the dot plots have the same scale for the X-axis. outputs
>
Notes: The text output of the analysis contains a summary of the inputs - specifically the number of data points, any skipped rows, and the number of groups. The analysis results include, for each group, the name of the group, the number of data points within the group, the mean, median, min, and max values within that group.

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Graphs: The graphs section consists of the dot plot of the data entered with each group plotted on a different chart. You can compare different groups of data to see if the individual points (dots) are relatively similar for each of the groups. All the charts should have the same horizontal scale.

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.

Examples

Following examples can be found in the Examples folder.
  • Create a dot plot for the data given in the file. The data represents the strength of components obtained from two suppliers (Component Supplier Strength.xlsm).
  • Create a dot plot for the number of passengers on a flight between two cities in a given month. What conclusions can you draw from this chart? (Flight Passengers.xlsm).
  • Create a dot plot for the price of homes in a metropolitan city. What conclusions can you draw from this chart? (Real Estate Prices.xlsm).