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Linear Regression on TI-83
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-83 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. It also calculates the value of the coefficient of determination, r
2
.
The TI-83 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 . 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-83 calculates the correlation coefficient r and the value of r
2
, the coefficient of determination.
