.. Copyright (C) Google, Runestone Interactive LLC This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/4.0/. .. _creating_line_of_best_fit: Creating a Line of Best Fit =========================== In order to analyze a line of best fit for a scatter plot, you will first need to make one. You can do this in Sheets through an option in the chart editor. After making a scatter plot, you can add a line of best fit by opening the chart editor by clicking the three dots in the top right corner. .. image:: figures/edit_chart.png :align: center :alt: Screenshot showing how to edit a chart by clicking the three dots in the top right corner. Once the chart editor is open, make sure customize is selected. Under “Series”, there is a checkbox to add a trendline. You can change the color and thickness of the line, display the :math:`R^{2}` value, (this is the same as the coefficient of determination), and display the equation of the line. .. image:: figures/add_trendline.png :align: center :alt: Screenshot showing how to add trendline. Once you have added a trendline, it will appear on your graph. .. image:: figures/average_sat_score_completion_rate.png :align: center :alt: Scatter plot with a trendline. Now that there is a trend line and equation of a line on the graph, you can use this information to analyze data and predict results given your data. In particular you can use the slope and y-intercept. Don't worry if you don't remember how to find this information from the equation of a line, the next section will guide you through this.