Calculator Notes for TI-89, TI-92 Plus, and Voyage 200

Note 13H • Least Squares Line (continued) TI-89/TI-92 Plus/Voyage 200
To display the slope, y-intercept, correlation coefficient, and coefficient of
determination, press 2nd [MATH] 6:Statistics 8:ShowStat ENTER .
To enter the equation of the least squares line into the Y Editor, say in y1,
type regeq(x)→y1(x) into the entry line on the Home screen, and press ENTER .
You can also use the Data/Matrix Editor or the Stats/List Editor to calculate
the least squares line. Follow the same procedure that you use to calculate a
median-median line (see Note 3D), but choose 5:LinReg for Calculation Type.
Note 13I • Nonlinear Regression
The calculator uses a least squares approach to fit a curve to nonlinear data.
It uses a combination of linearization and multivariable analysis.
You can find all of these nonlinear regression commands in the
6:Statistics 3:Regressions submenu:
[MATH]
2:ExpReg Exponential: y abx 3:QuadReg Quadratic: y ax2 bx c
4:PwrReg Power: y axb 5:LnReg Logarithmic: y a b ln(x)
7:CubicReg Cubic: y ax3 bx2 cx d
8:QuartReg Quartic: y ax4 bx3 cx2 dx e
9:SinReg Sinusoidal: y a sin(bx c) d
A:Logistic Logistic: y c1 a ebx 2nd
You enter each command followed by the names of the lists for the x- and
y-values separated by a comma.
The correlation coefficient, r, is not calculated for nonlinear regressions.
However, quadratic, cubic, and quartic regressions give the coefficient of
determination, R 2 .Some of the nonlinear regression commands have special
requirements:
Logarithmic regression must have all x-values greater than zero.
Exponential and logistic regressions must have all y-values greater than zero.
Power regression must have all x- and y-values greater than zero.
Quadratic and logistic regressions require at least 3 points; cubic and sinusoidal
regressions require at least 4 points; and quadratic regression requires at least
5points. In general, a regression command needs at least as many points as
there are parameters in the equation.
You can also use the Data/Matrix Editor or the Stats/List Editor to calculate
any of these regression models. Follow the same procedure that you use to
calculate a median-median line (see Note 3D), but choose the appropriate
regression model for Calculation Type.
Discovering Advanced Algebra Calculator Notes for the Texas Instruments TI-89, TI-92 Plus, and Voyage 200 CHAPTER 13 83
©2004 Key Curriculum Press