Scatter Plot Properties - Point Size

On the "Point size" tab of Scatter plot properties, you can change the size of the points in the plot. You can make all points on your map the same size (increasing or decreasing the size from the default), or can use point size as a way of providing additional information about your dataset, as in the example described here, and implemented in the image below.  If you want to show points of different sizes, you need to first select a dataset for determining the size distribution (left side of dialog box), and then an appropriate size classification mode.  Once the dataset has been divided into categories, you can left click in the boxes under "size" to edit the sizes assigned to each category of your grouped data.  To see how changes will affect your plot without closing the dialog box, use the "Apply" button in the lower right.  

If you choose point sizes that vary in time, you can check the interpolate values box (lower left corner) to smooth the transitions in an animation or map movie.  Also, you can choose a size for points where the covariate dataset contains a missing value in the lower right corner.

Choose "Preview" to view your selections in the map view (don't close the properties dialog box while you preview, or your changes will be lost).  When you have finished choosing a point size scheme, choose "OK" to apply your changes and close the dialog. If you press "Cancel" after "Preview" your changes will not be saved.

Click on tabs and boxes in the image below for more information.