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Least Squares Method—Finding the Line of Best Fit

                 Consider the following example, where marks of 10 students are shown, which they scored after a certain number of
                 hours of study:


                                                      No. of Hours Studied    Marks
                                                                 2              44

                                                                 9              98
                                                                 5              80

                                                                 3              75
                                                                 7              70

                                                                 1              63

                                                                 8              53
                                                                 6              92

                                                               2.5              71
                                                                 4              65


                 Assuming No. of Hours Studied as x and Marks as y, let us learn to plot the above data on a Scatterplot using Excel.

                                        120

                                        100

                                         80
                                       Marks (Y)   60



                                         40

                                         20


                                         0
                                           0     1    2     3    4     5    6     7     8    9    10
                                                               No. of Hours Studied (X)


                 We will also try to find the line that best fits the data i.e. the line that passes close to most of the data points. This line
                 is called the ‘Line of Best Fit’ or ‘Regression Line’.

                 Let us find the m (slope) and b (y-intercept) that suits that data
                 y = mx + b + e

                 Step 1: Type the given data in Excel.
                 Step 2: Select x and y. Click on Insert Chart → select the first scatter plot option.









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