Excel Guide #2: Creating the Model Equation

Once a graph is made in Excel, finding an equation which accurately models the data is important to determining how the two variables in the graph are related.
In Excel, one can use the “Trendline Fit” feature to add a fitted equation line/curve to the graph. Excel uses statistical methods to find the parameters of the equation, allowing the to user to have a model equation for the data graphed. Users must make sure the line/curve fit matches well with the data points as not all data will be related by the same functional form. Always make sure to inspect the fitted line/curve to the data to determine if the model line/curve accurately predicts the data points.

1. In order to create the model equation, click on one of the points on the graph. Afterwards, right click and pick the option that says “Add Trendline”.

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2. When the “Trendlines Options” box pops up, for this type of graph, because it is a linear line, click on “Linear”. There are other options for other types of graphs depending on what type of data you are collecting. After clicking on “Linear” for the trend line, to find out the equation of the line, click the option that says “Display Equation on chart”. This will show the equation of the trend line on the graph.

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