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Drawing a Logarithmic Regression Graph
Logarithmic regression expresses
y
as a logarithmic function of
x
. The normal logarithmic
regression formula is
y
=
a
+
b
· ln(
x
). If we say that X = ln(
x
), then this formula corresponds
to the linear regression formula
y
=
a
+
b
·X.
u
ClassPad Operation
Start the graphing operation from the Statistics application’s Graph window or List window.
From the Graph window
Tap [Calc] [Logarithmic Reg] [OK] [OK]
"
.
From the List window
Tap [SetGraph][Setting...], or
G
.
On the Set StatGraphs dialog box that appears, configure a StatGraph setup with the
setting shown below, and then tap [Set].
Type: LogR
Tap
y
to draw the graph.
7-5-9
Graphing Paired-Variable Statistical Data
The following is the logarithmic regression model formula.
y
=
a
+
b
·ln(
x
)
a
: regression constant term
b
: regression coefficient
r
: correlation coefficient
r
2
: coefficient of determination
MSe
: mean square error
• MSe =
Σ
1
n – 2
i=1
n
(y
i
– (a + b·ln (x
i
)))
2