Excel multiple regression can be performed by adding a trendline, or by using the Excel Data Analysis Toolpak. If you just want to know the equation for the line of best fit, adding a trendline will work just fine. If you want to know more detailed information, like the standard error of a sample, then use the Excel Data Analysis Toolpak method.
Excel Multiple Regression: Adding a Trendline
Example question: Find the equation for the third degree polynomial that fits the following data:
Step 1: Type your data into two columns. The x-values should be in one column (i.e. column A); the y-values should be in an adjacent column.
Step 2: Highlight both columns of data.
Step 3: Click “Insert” and then click “Scatter.” Choose the first scatter plot (Scatter with only Markers).
Step 4: Click on one of the data points on the graph. This will highlight all the points.
Step 7: Click “Display Equation on chart” at the bottom of the pop up window, and then press “Enter.”
Excel Multiple Regression: The Data Analysis Toolpak
Step 1: Type your data in (as in step 1 above).
Step 2: Add a second column containing cubes of your x-values. For this example, cube each of the x-values in column “B”.
Step 2: Click the “Data” tab and then click “Data Analysis.”
Step 3: Select BOTH columns (the x-values and their squares) when choosing x-values on the pop up window. Choose the appropriate column for the y-values.
Step 4: Check the labels box if you have column headers.
Step 6: Select an output area. Press OK.
For help with understanding what the output means, see: Excel Regression Analysis Output Explained.