6-12
Cubic regression
Model formula.......
y = ax
3
+ bx
2
+ cx + d
a
..........regression third coefficient
b.......... regression second coefficient
c..........regression first coefficient
d.......... regression constant term
(
y-intercept)
Quartic regression
Model formula.......
y = ax
4
+ bx
3
+ cx
2
+ dx + e
a
..........regression fourth coefficient
b.......... regression third coefficient
c..........regression second coefficient
d.......... regression first coefficient
e..........regression constant term (y-intercept)
I Logarithmic Regression Graph
Logarithmic regression expresses y as a logarithmic function of x. The standard logarithmic
regression formula is
y = a + b × In x, so if we say that X = In x, the formula corresponds to
linear regression formula
y = a + bX.
(CALC)(E)(Log)
(DRAW)
The following is the logarithmic regression model formula.
y = a + b·ln x
a
..............regression constant term
b..............regression coefficient
I Exponential Regression Graph
Exponential regression expresses y as a proportion of the exponential function of x. The
standard exponential regression formula is
y = a × e
bx
, so if we take the logarithms of both
sides we get In y = In a + bx. Next, if we say Y = In y, and A = In a, the formula corresponds to
linear regression formula Y = A +
bx.
(CALC)(E)(Exp)
(
aeˆbx) or (abˆx)
(DRAW)
The following is the exponential regression model formula.
y = a·e
bx
a..............regression coefficient
b..............regression constant term
y = a·b
x
a..............regression constant term
b..............regression coefficient
Quadratic regression
Model formula.......
y = ax
2
+ bx + c
a
..........regression second coefficient
b.......... regression first coefficient
c..........regression constant term
(y-intercept)
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