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Line of Best Fit(Eyeball Method)

A line of best fit is a straight line drawn through the maximum number of points on a scatter plot balancing about an equal number of points above and below the line.

It is used to study the nature of relation between two variables.

  

The line of best fit in the scatter plot above rises from left to right; so, the variables have a positive correlation .

Here, the line of best fit drops from left to right, so the variables have a negative correlation.

Example 1:

Draw a line of best fit for the scatter plot given.

Solution:

Draw a line through the maximum number of points, balancing about an equal number of points above and below the line.

Example 2:

Draw a line of best fit for the scatter plot given.

Age of a Person (in years) ( x ) Annual Income (in $)( y )
32 75000
40 110000
35 90000
36 50000
37 45000
39 60000
34 51000
39 60000
41 40000
45 100000
47 65000
49 68000
53 105000
55 85000
43 80000
44 55000
50 85000

Solution:

Plot the age in the x -axis and the income in the y -axis and mark the points.

Draw a line through the maximum number of points balancing about an equal number of points above and below the line.