The median-median method is most often used when the distribution has a large quantity of data and is particularly effective when this distribution includes inconsistent data. This method has several steps:

• Arranging the points so that the x values are in ascending order (if two x values are identical, they are ordered based on the y value);
• Separating the points on the scatter plot into three groups of equal frequencies (so that the difference between the number of data in each group is minimal);
• For each group, determining the median of the x coordinates and the median of the y coordinates M₁ (x, y), M₂ (x, y) and M₃ (x, y);
• Determining the mean of the x coordinates and the mean of the y coordinates of the three median points: P₁ ([latex]\overline{x},  \overline{y}[/latex]
• Positioning the coordinate points M₁ (x, y) and M₃ (x, y) and drawing a line through them;
• The line of regression is parallel to the line that passes through the points M₁ (x, y) and M₃ (x, y);
• The line of regression passes through the point P₁ ([latex]\overline{x},  \overline{y}[/latex]);
• The y-intercept P₂ (0, y) of the line of regression is calculated using the point P₁([latex]\overline{x},  \overline{y}[/latex]) and the slope of the line that passes through M₁(x, y) and M₃ (x, y).