Interpreting and describing dataLine of best fit

The 'line of best fit' is a line that goes roughly through the middle of all the scatter points on a graph.

The closer the points are to the line of best fit the stronger the correlation is.

The line of best fit is drawn so that the points are evenly distributed on either side of the line. There are various methods for drawing this 'precisely', but you will only be expected to draw the line 'by eye'.

You may be asked to comment on the nature of the correlation, meaning whether there is a positive, negative or no correlation.

Using the term 'strong correlation' is appropriate if all of the points are very close to the line of best fit.

When drawing the line of best fit, use a transparent ruler to see how the line fits between all the points before you draw it.

Example

The heights and weights of twenty children in a class are recorded. The results are shown on the scattergraph below.

As the line of best fit is drawn 'by eye', it is unlikely your answer will be exactly the same as someone else's answer.

Sometimes you are given the equation of the line of best fit. You can use this in estimation.

Example