Education Technology

# Knowledge Base

## Solution 11919: Calculating Cubic Regressions on the TI-83 Family, TI-84 Plus Family or TI-Nspire™ Handheld in TI-84 Plus Mode Graphing Calculator.

### How do I calculate a cubic regression on a TI-83 family, TI-84 Plus family or TI-Nspire Handheld in TI-84 Plus mode graphing calculator?

The example below will demonstrate how to calculate a cubic regression.

Example: Find the cubic regression equation for the x and y values below.
xStat: {80, 84, 86, 91, 93, 96}
yStat: {10, 7, 9, 18, 19, 15}

To enter the data:
1) Enter STAT edit mode by pressing [STAT] [ 1 ].
2) Enter the data in the L1 and L2 lists, pressing [ENTER] after each entry.
3) Press [2nd] [QUIT] to leave the editor.

To calculate the cubic Regression (ax3+bx2+cx+d):
1) Enter the STAT mode again by pressing [STAT].
2) Select CALC.
3) Press [6] to select CubicReg.
4) Specify which lists to use for the regression, press [2nd] [L1] [ , ] [2nd] [ L2].
5) Press [ENTER] to perform the regression calculation.

The calculator will display the form of the equation (y=ax3+bx2+cx+d) and then list the values for the coefficients.

Please see the TI-83 family and TI-84 Plus family guidebooks for additional information.

Please Note: TI-Nspire users may refer to the TI-84 Plus family guidebook.