Texas Instruments TI-84 Plus - Quadreg (Ax2+Bx+C); Cubicreg - (A3+B2+C+D); Quartreg - (A4+B3+C2+DX+E)

Chapter 12: Statistics 309
LinReg(ax+b) [Xlistname,Ylistname,freqlist,regequ]
QuadReg (ax
QuadReg (axQuadReg (ax
QuadReg (ax
2
+bx+c)
+bx+c)+bx+c)
+bx+c)
QuadReg (quadratic regression) fits the second-degree polynomial y=ax
2
+bx+c to the
data. It displays values for
a, b, and c; when DiagnosticOn is set, it also displays a value
for
R
2
. For three data points, the equation is a polynomial fit; for four or more, it is a
polynomial regression. At least three data points are required.
QuadReg [Xlistname,Ylistname,freqlist,regequ]
CubicReg—(a
CubicReg—(aCubicReg—(a
CubicReg—(ax
xx
x
3
+b
+b+b
+bx
xx
x
2
+c
+c+c
+cx
xx
x+d)
+d)+d)
+d)
CubicReg (cubic regression) fits the third-degree polynomial y=ax
3
+bx
2
+cx+d to the
data. It displays values for
a, b, c, and d; when DiagnosticOn is set, it also displays a
value for
R
2
. For four points, the equation is a polynomial fit; for five or more, it is a
polynomial regression. At least four points are required.
CubicReg [Xlistname,Ylistname,freqlist,regequ]
QuartReg—(a
QuartReg—(aQuartReg—(a
QuartReg—(ax
xx
x
4
+b
+b+b
+bx
xx
x
3
+c
+c+c
+cx
xx
x
2
+ dx+e)
+ dx+e)+ dx+e)
+ dx+e)
QuartReg (quartic regression) fits the fourth-degree polynomial y=ax
4
+bx
3
+cx
2
+dx+e to
the data. It displays values for
a, b, c, d, and e; when DiagnosticOn is set, it also displays
a value for
R
2
. For five points, the equation is a polynomial fit; for six or more, it is a
polynomial regression. At least five points are required.