Linear Regression


The linear regression option finds the equation of a linear equation of the form y = ax + b or y = a + bx that best fits a set of data. First, enter the data . Press  



Press  and use  to select CALC. Press  This yields an equation of the form y = ax + b.

 


The linear regression option can also be obtained by pressing . This yields an equation of the form y = a + bx.

 


The resulting equations are equivalent, y = 0.24x + 1.14 and y = 1.14 + 0.24x. The TI-82 calculates the correlation coefficient, r. In this case, r is about 0.91. The value of r lies between -1 and 1, inclusive. It is a measure of how well the regression equation fits the data. A value of -1 or 1 indicates a perfect fit.

The TI-82 stores the regression equation. The equation can be graphed and is transfered to  without typing the equation as follows. Press    and use  to select EQ.



Press  to view the regression equation and press . The equation is now entered in . Press . The data points can also be viewed. Access STAT PLOTS by pressing    to turn the plots on. Press .




Note: The resulting linear equation is an exact fit if two nonvertical data points are entered.

The TI-82 calculates the correlation coefficient r.