20070201
k Quadratic/Cubic/Quartic Regression Graph
A quadratic/cubic/quartic regression graph represents connection of the data points of a
scatter diagram. It uses the method of least squares to draw a curve that passes close to
as many data points as possible. The formula that represents this is quadratic/cubic/quartic
regression.
Ex. Quadratic regression
1(CALC)4(X^2)
6(DRAW)
Quadratic regression
Model formula .......
y = ax
2
+ bx + c
a
...............regression second coeffi cient
b...............regression fi rst coeffi cient
c ...............regression constant term ( y-intercept)
r
2
.............coeffi cient of determination
MSe ........mean square error
Cubic regression
Model formula .......
y = ax
3
+ bx
2
+ cx + d
a
...............regression third coeffi cient
b...............regression second coeffi cient
c ...............regression fi rst coeffi cient
d...............regression constant term ( y-intercept)
r
2
.............coeffi cient of determination
MSe ........mean square error
Quartic regression
Model formula .......
y = ax
4
+ bx
3
+ cx
2
+ dx + e
a...............regression fourth coeffi cient
b...............regression third coeffi cient
c ...............regression second coeffi cient
d...............regression fi rst coeffi cient
e ...............regression constant term ( y-intercept)
r
2
.............coeffi cient of determination
MSe ........mean square error
6-3-7
Calculating and Graphing Paired-Variable Statistical Data
