Scatter Diagrams  
Summary 
a scatter diagram or scattergram is used to display the results when two sets of data are compared to see if there is a relationship between them. if all of the points lie on or near a straight line there is said to be a linear correlation between the two sets of data. a linear correlation can be positive , as one quantity increases so does the other. the line that best fits the points is called the trend line, the line of best fit or the regression line. 
Key Skills 

Vocabulary 
scattergram, scatter diagram, regression, line of best fit, correlation. 