Scatter Graphs
By Dhara Rami

Scatter graph is a graph, which help to plot the information on two related variables. It consists of plotted points, which are scattered all around the X-Y grid. The main use of the scatter graph is to visualize the strength of the co-relation between the two metrics. It can also be said that scatter graphs are used to create the relationship between two variables for a set of paired data. They are mainly used in Science to study relationships between two variables. So it has been found that the pattern of the scatter describes the relationship and the trend lines should follow a trend of the data. Join as many points as possible and leave an equal number of unconnected points on either side.

Scatter graph is a graph, which is like the basic line graphs and require minimum of two numeric data attributes. The pattern of the scatter graph reveals a relationship between the two variables measured by the X and Y axes or in the case of a 3 dimensional form, it will be among the three variables which are measured by X, Y, and Z axes). In a 2 dimensional scatter graphs; one can illustrate trends in the plotted points by just adding a regression curve. It has been noted that the scatter graphs can show multiple data sets, each of which is represented by a different symbol, and each will have any number of data points.

Scatter graph are the one, which clearly establish the data correlation and is one of the best
method to illustrate a non-linear pattern. It can be used for data extrapolation and interpolation. A scatter graph generally shows the discrete values which don't occur at regular intervals or which belong to a series. That makes it different from a line graph, which are drawn using only the symbols.

One of the main advantages of a scatter graph is that it demonstrates a typical relationship, which is generally not so clear in various graphing methods normally used. While using standard functions in the Graphics Server DLL, we can define a scatter graph by normally supplying an X position for each data point. It should also be noted that when we use a Graph Control or when we use Graphics Server's autograph DLL, no X positions is supplied and the it will place points at X increments of 1 automatically, starting at 0.

It should be noted that in 3 dimensional (3D) scatter graphs, Z positions are not handled in this way and we needs to supply a Z value for each and every point. We can display scatter plots alone, curves alone, or both while using a 2 dimensional (2D) scatter graphs. While in a 3D scatter graphs, its totally different and we can connect points in the same set with a continuous line. Also we can drop a vertical line from each point.

The limitation of a scatter graph is that, they can just show relationship between two variables at a time. They can also show incorrect graph analysis if there are only few data points available.