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Scatter plot

Use scatter plots to visualize the relationship between two numeric variables, where one variable is displayed on the x-axis, and the other variable is displayed on the y-axis. For each record, a point is plotted where the two variables intersect in the chart. When the resulting points form a nonrandom structure, a relationship exists between the two variables.

Variables

Scatter plots are made up of two Numbers, one for the x-axis and one for the y-axis.

Statistics

A regression equation is calculated and the associated trend line and R2 are plotted on scatter plots. The trend line models the linear relationship between x and y, and the R2 quantifies how well the data fits the model. This is only relevant for linear relationships. To turn off the trend line, uncheck the Show linear trend checkbox in the Chart Propertiespane, or toggle visibility by clicking the item in the legend. To change the color of the trend line, click the trend line color swatch in the Chart Propertiesand choose a new color.

Learn more about regression analysis

Correlation

When small x values correspond to small y values, and large x values correspond to large y values (line sloping up), this indicates a positive correlation. When small x values correspond to large y values, and large x values correspond to small y values (line sloping down), this indicates a negative correlation.

Note:

It is important to note that x being correlated to y does not imply that x causes y.

Axes

Axis bounds

Default minimum and maximum axis bounds are set based on the range of data values represented on the axis. These values can be customized by typing in a new desired axis bound value. Clicking the reset icon will revert the axis bound back to the default value.

Log axis

By default, scatter plot axes are displayed on a linear scale. One or both axes can be displayed on a logarithmic scale by checking the Log axis checkbox in the Axes section of the Chart Properties pane.

Logarithmic scales are useful when visualizing data with large positive skew, where the bulk of data points have a small value, with a few data points with very large values. Changing the scale of the axis does not change the value of the data, just the way it is displayed.

Linear scales are based on addition, and logarithmic scales are based on multiplication.

On a linear scale, each increment on the axis represents the same distance in value. For example, in the axis diagram below, each increment on the axis increases by adding 10.

Linear scale axis

On a logarithmic scale, increments increase by magnitudes. In the axis diagram below, each increment on the axis increases by multiplying by 10.

Logarithmic scale axis
Note:

Logarithmic scales cannot display negative values or zero. If you chose to log the axis of a variable with negative values or zero, those values will not appear on the chart.

Number format

You can format the way an axis will display numeric values by specifying a number format category or by defining a custom format string.

Appearance

Titles and description

Charts and axes are given default titles based on the variable names and chart type. These can be edited on the General tab in the Chart Properties pane. You can also provide a chart Description, which is a block of text that appears at the bottom of the chart window.

Visual formatting

When a chart window is active, a Chart Format context ribbon becomes available, allowing visual formatting of the chart. Chart formatting options include the following:

  • Changing the size, color, and style of the font used for axis titles, axis labels, description text, and legend text
  • Changing the color, width, and line type for grid and axis lines
  • Changing the background color of the chart

Color

Scatter plots inherit their outline and fill colors from the source layer symbology. By symbolizing a layer with a different attribute than either of the scatter plot variables, a third variable can be shown on the scatter plot visualization.

Example

Create a scatter plot to visualize the relationship between diabetes and hypertension among Medicare beneficiaries. Select features in the chart to see where they fall on the map.

  • X-Axis— Diabetes rate
  • Y-Axis— Hypertension rate

Scatter plot showing relationship between diabetes and hypertension among Medicare beneficiaries