Suppose n observations of a data are (x₁, y₁), (x₂, y₂), …….. (x_n, y_n) based on a sample drawn from a bivariate population. From this data we have to fit the line of regression of Y on X. First of all, we will draw scatter diagram by plotting the n pairs of observations (x₁, y₁), (x₂, y₂), …….. (x_n, y_n). We will draw a line in such a way that it is close to almost all the points of the scatter diagram and gives the best estimate of relationship between Y and X.

Such line of best fit is called the regression line of, Y on X. We can find the equation of the regression line by choosing any two points on the line. This equation is called the regression line. This method to fit the line of regression is easy and quick and does not require any computation.

Limitations:

• The regression line obtained by this method does not give the best estimate of relation between Y and X.
• In this method, from the same data, different persons can select different points and get the different regression lines. Hence, using them the conclusions derived are different.
• This method is not objective but it is rather subjective in sense.