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Drawing Quadratic, Cubic, and Quartic Regre
You can draw a quadratic, cubic, or quartic regression graph based on the plotted points.
These graphs use the method of least squares to draw a curve that passes the vicinity of
as many data points as possible. These graphs can be expressed as quadratic, cubic, and
quartic regression expressions.
The following procedure shows how to graph a quadratic regression only. Graphing the cubic
and quartic regressions are similar.
Cla
Pad Operation (Quadratic Regre
Start the graphing operation from the Statistics application's Graph window or List window.
From the Graph window
Tap [Calc] [Quadratic Reg] [OK] [OK]
• For cubic regression tap [Cubic Reg] and for quartic regression tap [Quartic Reg]
instead of [Quadratic Reg].
From the Li t window
Tap [SetGraph][Setting...], or
On the Set StatGraphs dialog box that appears, configure a StatGraph setup with the
setting shown below, and then tap [Set].
Type: QuadR
• For cubic regression select [CubicR] and for quartic regression tap [QuartR] instead
of [QuadR].
Tap
to draw the graph.
The following are the model formulas for each type of regression.
Quadratic Regre
Model Formula:
a
:
quadratic regression coefficient
b
:
linear regression coefficient
c
:
regression constant term (
2
r
:
coefficient of determination
MSe
: mean square error
1
• MSe =
n – 3
7-5-7
Graphing Paired-Variable Statistical Data
.
ion
2
y
a
x
b
x
c
=
·
+
·
+
y
-intercept)
n
2
(y
– (a·x
+ b·x
+ c))
i
i
i
i=1
20060301
ion Graph
ion)
.
2
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