A scatter diagram is a way of visually representing information on two variables on a graph. You can get 3 possible outcomes with scatter diagrams, these are:

  1. Positive correlation: Both variables increase or both variables decrease.
  2. Negative correlation: One variable increases while the other decreases.
  3. No correlation: There is no pattern that you can identify as the data is randomly spread on the graph.

Scatter diagrams are also used for estimating. Using a ‘Best Fit’ line you can estimate the required information using the line drawn. Below are points to bear in mind when drawing Best Fit lines.

Best Fit lines & Estimating


Estimate the Area under a Curve
Completing a Cumulative Frequency Table