20050501
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
(yi – (a + b·ln (xi)))
2
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