Find the Correlation on Different Scatter Graphs

A scatter graph is used to display the results of two variables.  

There may or may not be a connection (correlation) between the two variables.

 

Example

The weights and heights of 10 children are plotted on a scatter graph.  The results are shown below.

 

 

This shows that the heavier a child is, the taller he/she is.

There is a definite connection between weight and height.

This is known as a positive correlation.

 

We can draw a line that best fits this data.  It goes in the direction of the plotted points and has roughly the same number of points above it as below.

It is known as the line of best fit.

 

 

The following scatter graphs show negative correlation and no correlation.

 

             

    negative correlation                     no correlation

 

It would be possible to draw a line of best fit on the graph with negative correlation, but not on the one with no correlation.

 

Shall we move on to the questions now?