# HP 50g User Manual Page 579

Graphing calculator.

Where s
, s
are the standard deviations of x and y, respectively, i.e.
x
y
2
s
x
The values s
and r
xy
obtained by using the "Fit data" feature of the calculator.
Linearized relationships
Many curvilinear relationships "straighten out" to a linear form. For example,
the different models for data fitting provided by the calculator can be linearized
as described in the table below.
Type of
Fitting
Linear
y = a + bx
Log.
y = a + b ln(x)
Exp.
Power
The sample covariance of
Also, we define the sample variances of
2
s
The sample correlation coefficient r
1
n
(
x
i
n
1
i
1
are the "Covariance" and "Correlation," respectively,
xy
Actual
Model
bx
ln(y) = ln(a) + bx
y = a e
b
ln(y) = ln(a) + b ln(x)
y = a x
is given by
1
n
(
i
n
1
i
1
2
2
x
)
s
y
n
Linearized
Model
[same]
[same]
s
and , respectively, as
2
2
)
s
s
r
is
s
1
n
(
y
y
i
1
i
1
Indep.
Depend.
variable
Variable
x
y
ln(x)
y
x
ln(y)
ln(x)
ln(y)
1
(
i
n
1
1
n
(
i
n
1
i
1
s
2
)
Covar.
s
s
xy
s
ln(x),y
s
x,ln(y)
s
ln(x),ln(y)
)(
)
i
2
)
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