Scatter Plot

What it is

The Scatter plot displays unaggregated, row-level data as points, plotting the points along an x and y axis. Each axis represents a quantitative measure. You can size or color points by further measures, making the scatter plot capable of representing up to four measures for each group (x, y, size, and color). Scatter plots resemble Bubble charts, but are used to view unaggregated data while Bubble charts aggregate data.

When to use it

Similar to Bubble chart, use a Scatter plot when you want to study the correlation between two measures, or simply visualize the distribution of data to spot outliers or patterns. Scatter plots can be used to visualize any sized dataset, but they really shine in their ability to visualize large amounts of data.

How to set it up

The animation below shows a scatter plot being created for an airline flights dataset, with each point representing a flight, the x and y axes representing flight arrival delay and departure delay, size representing the flight duration, and color representing the airline carrier.

On the right hand side of the screen, a popup box is configured, which displays columns of information whenever one of the points on the map is moused over.

Note also that once the Size measure is added on the left of the screen, controls become available on the right of the screen for “Domain” and “Range.” Domain is used to establish limits on the data that is considered for sizing, Range is used to set the range of sizes (in pixels) for the points. Domain and Range controls function in the same way in the Pointmap chart type, and a more detailed explanation of these controls’ use can be found in section Size Domain.

Zoom and Selection

You can zoom in on specific areas of a Scatter plot chart and select arbitrary sets of data points using the selection tools.

Zoom

You can select and zoom a specific region of a Scatter plot chart. Hold the shift key, then drag a rectangular selection around the area on which you want to zoom. You can also zoom in and out using a mouse scrolling button.

Selection

You can select a subset of the points in a Scatter plot using the Circle, Polygon, and Lasso selection tools.

Circle Selector

Use the Circle tool to select an area around a specific central point. Click the Circle tool icon, then click anywhere on the map to create a circular selection.

To move the circle, click anywhere inside the selected area to select the circle. Drag the circle to the new location.

To resize the circle, click anywhere inside the selected area, then drag any of the white squares to scale the circle up or down. Drag the white squares at the midpoints to scale in only one direction. Hold the Shift key to maintain the relative proportions of the selection. Hold the Alt key to scale the selection from the center outward.

Polygon Selector

Use the Polygon tool to select an area with noncomplex angles. Click to set each point. As you draw the selection, you can hold the Shift key to contrain each line to 45° angle increments relative to the previous line.

To complete the selection, do one of the following:

• Double-click
• Click the starting point a second time
• Press Enter

To change the size of the selection, click anywhere in the selected region. Drag any of the white corner dots to resize the selection. Hold the Shift key to constrain the relative proportions of the selection. Hold the Alt key to scale the selection from the center.

To rotate the selection, mouse hover over any corner to display a curved arrow. Click and drag to rotate. Hold the Shift key to rotate in 45° increments.

To edit the endpoints in the selection, double-click anywhere in the region. Drag the white endpoints to new locations. To add an endpoint, click one of the small orange dots in the middle of a line segment; it becomes a new endpoint that you can drag to your desired position. To delete an endpoint, hold the Alt key and click the endpoint.

Note that if you create a selection where lines intersect the behavior is undefined and has unpredictable results.

Lasso Selector

Use the Lasso tool to trace around an area with curves or complex angles. Click to start, drag to draw the outline of your desired area, then release the mouse at any time to complete the selection with a straight line.

Once you have created your selection, the selection points are simplified, and you can edit or update the selection as you would a selection made with the Polygon tool.