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Scatter graph

The scatter graph lets you plot data points based on two independent variables.

The scatter graph consists of plotted points "scattered" around an X-Y grid. The pattern may reveal a relationship between the two variables measured by the X and Y axes (or, in 3D form, among the three variables measured by the X, Y, and Z axes). In 2D scatter graphs, you can illustrate trends in the plotted points by adding a regression curve.

Generally, a scatter graph shows discrete values that don’t occur at regular intervals or belong to a series--making it unlike a line graph drawn with symbols only, which usually plots a regular series of points.

• Scatter graphs can chart multiple data sets, each represented by a different symbol, each having any number of data points.
  
  
• In defining a scatter graph, you usually supply an X position for each data point (and must do so if you’re using standard functions in the Graphics Server DLL). In the Graph Control and under Graphics Server’s AutoGraph DLL, you can supply no X positions and Graphics Server will automatically place points at X increments of 1, starting at 0. (Note that Z positions aren’t handled this way in 3D scatter graphs; you must supply a Z value for each point.)
  
  
• In 2D scatter graphs, you can display scatter plots alone, curves alone, or both together.
  
  
• In 3D scatter graphs, you can connect points in the same set with a continuous line. You can also drop a vertical line from each point to the floor of the cage.
  
  

Use a scatter graph...

• To view actual measurements or observations on a grid, possibly revealing patterns and trends in those data.
  
  
• With plotted points alone when you want to show the data empirically, without suggesting a relationship between the X and Y variables.
  
  
• With a curve alone when you want to show the relationship between the X and Y variables as suggested by the data, irrespective of the actual data points.
  
  
• With both plotted points and a curve when you want to show the empirical data as well as suggest trends.
  

By adding curves to a scatter graph, you can suggest trends in the plotted values.
The 3D form of the scatter graph lets you plot points based on three variables.

Other graph types to consider

• When you're graphing two variables but data points fall at uniform intervals along the X axis, you should generally use a line graph with symbols instead of a 2D scatter graph.
  
  
• When you're graphing against three variables, consider a bubble graph, which is generally easier to read than a 3D scatter graph. Instead of using three axes (X, Y, and Z), bubble graphs plot "bubbles" of different sizes along an X and a Y axis. The third variable is shown by the size of each bubble.