How to Find Linear Regression Slope: Overview
Remember from algebra, that the slope is the “m” in the formula y = mx + b.
In the linear regression formula, the slope is the a in the equation y’ = b + ax.
They are basically the same thing. So if you’re asked to find linear regression slope, all you need to do is find b in the same way that you would find m.
Calculating linear regression by hand is tricky, to say the least. There’s a lot of summation (that’s the Σ symbol, which means to add up). The basic steps are below, or you can watch a video on how to Find a linear regression equation. The video goes into a lot more detail about how to do summation. Finding the equation will also give you the slope. If you don’t want to find the slope by hand (or if you want to check your work), you can also use Excel. Scroll to the bottom for the video on how to find linear regression slope in Excel.
How to Find Linear Regression Slope: Steps
Step 1: Find the following data from the information given: Σx, Σy, Σxy, Σx2, Σy2. If you don’t remember how to get those variables from data, see this article on how to find a Pearson’s correlation coefficient. Follow the steps there to create a table and find Σx, Σy, Σxy, Σx2, and Σy2.
Step 2: Insert the data into the b formula (there is no need to find a).
If formulas scare you, you can find more comprehensive instructions on how to work the formula here: How to find a linear regression equation.
How to Find Regression Slope in Excel 2013
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