How To Plot Least Squares Regression Line On Excel. If we wanted to draw a line of best fit, we could calculate the estimated grade for a series of time values and then connect them with a ruler. You can calculate the values of the residuals manually in excel or you can use assayfit pro or another curve fitting program to do it.

Choose the options tab and select display equation on chart (figure 3): In excel, click data analysis on the data tab, as shown above. Click ok to close the dialogue.