How to find the Linear Regression Equation

This question comes from Busisiwe, who studies at the University of Stellenbosch.

How do you find the equation for linear regression?

It is quite easy once you know how – and all the stats functionality works the same way.

So for linear regression:

On your calculator press MODE and choose 1 for STAT

Then press number 1 to choose line (for linear regression).

To enter the data type it in as coordinates – your x value first then press the button above change and then type in your y-value. Then press the button – it should now say data set = 1 (if this is the first value you entered). Do the same for the rest of your data set.

If you would like to see the data you have input press your up button or down button arrow keys. Once you have finished checking your data press on. If you see there is an error and you want to change something simply move the blue block to the space where the error is (e.g. next to the x or y) type in the new/ correct value and press Change.

Once you have finished typing in your data and you are happy with it press on (this is just if you still have data displayed on your screen.

To find the equation of the regression line:

Your equation is y = a +bx.

Your b is your gradient and you’re a is your y-intercept.

To get your gradient press the blue key and then press the button. (you will see above this button in blue it says b) then press and viola – here is your gradient.

To get the y-intercept press and the button and .

To get the correlation co-efficient press , , .

So for any stats value press the blue key then find the blue function on your number keypad and press it, and then press . For example, the average value of the x values is found by pressing , , .

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