Scatterplots and dot plots

There are several broad categories of charts created with the point graphic element:

  • Scatterplots. These are useful for plotting multivariate data. They can help you determine potential relationships among scale variables. A simple scatterplot uses a 2-D coordinate system to plot two variables. A 3-D scatterplot uses a 3-D coordinate system to plot three variables. When you need to plot more variables, you can try overlay scatterplots and scatterplot matrices (SPLOMs). An overlay scatterplot displays overlaid pairs of x-y variables, with each pair distinguished by color or shape. A SPLOM creates a matrix of 2-D scatterplots, with each variable plotted against every other variable in the SPLOM.
  • Dot plots. Like histograms, these are useful for showing the distribution of a single scale variable. The data are binned, but, instead of one value for each bin (like a count), all of the points in each bin are displayed and stacked. These graphs are sometimes called density plots.
  • Summary point plots. These are just like a bar chart, except that points are displayed where the top of the bars would have appeared. Because the summary point plot is so similar to a bar chart, refer to Bar charts for information about creating it.
  • Drop-line charts. These are a special type of summary point plot. The points are grouped and a line is drawn through the points in each category. The drop-line chart is useful for comparing a statistic across categorical variables.

How to create a simple scatterplot

  1. In the Chart Builder, click the Gallery tab and select Scatter/Dot in the Choose From list.
  2. Drag the Simple Scatter icon onto the canvas.
  3. Drag a scale variable to the x-axis drop zone.
  4. Drag another scale variable to the y-axis drop zone. There is no need to specify a statistic, because scatterplots typically display raw values.

How to create an overlay scatterplot

  1. In the Chart Builder, click the Gallery tab and select Scatter/Dot in the Choose From list.
  2. Drag the Simple Scatter icon onto the canvas.
  3. Drag a scale variable to the x-axis drop zone.
  4. Drag multiple scale variables to the y-axis drop zone. You can select multiple variables by holding down the Ctrl key while selecting each variable.

    The last action creates pairs of variables that are drawn as a group. The variable on the x axis is paired with each variable on the y axis. To edit the pairs, open the Element Properties dialog box and select Point1 in the Edit Properties Of list. You can also continue to add more variables to the y axis.

How to create a scatterplot matrix

  1. In the Chart Builder, click the Gallery tab and select Scatter/Dot in the Choose From list.
  2. Drag the Scatterplot Matrix icon onto the canvas.
  3. Drag multiple scale variables to the Scattermatrix drop zone.

    Each variable in the drop zone is plotted against every other variable to create a matrix of individual scatterplots. To edit the variables, open the Element Properties dialog box and select Scattermatrix1 in the Edit Properties Of list.

How to create a simple dot plot

  1. In the Chart Builder, click the Gallery tab and select Scatter/Dot in the Choose From list.
  2. Drag the Simple Dot Plot icon onto the canvas.
  3. Drag a scale variable to the x-axis drop zone.

Note: The "statistic" for a dot plot is Dot Plot. You cannot change this.

How to create a drop-line chart

  1. In the Chart Builder, click the Gallery tab and select Scatter/Dot in the Choose From list.
  2. Drag the Drop-line icon onto the canvas.
  3. Drag a categorical variable to the x axis.
  4. Drag another categorical variable to the Set Color grouping zone.
  5. Specify a statistic in the Element Properties dialog box. The result of any statistic determines the position of the point for each combination of categories. A line connects the lowest and highest point in each x-axis category. If the statistic you want does not appear in the Statistic list, it may require a variable. Drag a scale variable to the y-axis drop zone and check if the statistic is now available.

Additional features

Point ID. You can use a variable for labeling the points. Click the Groups/Point ID tab and select Point ID Label. This action adds a new drop zone to the canvas. Drag the variable you want to use for labeling to the new drop zone.

Grouping. You can specify a categorical variable for creating groups of points. This is useful for comparing the values of the groups. For more information about grouping, see Adding and editing grouping variables . The gallery also provides grouped scatterplots and dot plots. Grouping is not available for overlay scatterplots because the variable pairs are already groups.

Paneling. Paneling creates a table of charts, with a cell for each category in the paneling variable. See the topic Adding Paneling Variables for more information.