Quadratic regression
Formula for quadratic regression:
•
y = A + Bx + Cx
2
▶ ▶
Press
SHIFT
S-SUM
▶ ▶
Press
SHIFT
S-SUM
▶ ▶
Press
SHIFT
S-SUM
▶ ▶
Press
SHIFT
S-VAR
▶ ▶ ▶
Press
SHIFT
S-VAR
▶ ▶ ▶
Press
SHIFT
S-VAR
▶ ▶ ▶
Press
SHIFT
S-VAR
•
Example:
Calculate the regression formula coeffi cients for the following data. Calculate the
estimated value of y for x
MODE MODE
SHIFT
2 , 9
Coeffi cient A = -1.8
Coeffi cient B = 6.621428571
Coeffi cient C = -0.589285714
y (if x
x
x
DE FR EN ES
to calculate the sum of cubes of x data (∑x
1
to calculate the sum of the products of x-data squares and y data (∑x
2
to calculate the sum of biquadrates of x data (∑x
3
to calculate regression coeffi cient C
3
to calculate the estimated value of x
1
to calculate the estimated value of x
2
to calculate the estimated value of y (y)
3
= 9 and the estimated value of x for y
i
x
2
4
6
8
10
▶
(REG)
2
=
1
CLR
4 , 15
DT
DT
=9) = 10.06071429
i
(if y
=4) = 0.957544233
1
i
=4) = 10.2788194
(if y
2
i
EN
= 4.
i
y
9
15
18
12
6
(Quad)
3
6 , 18
8 , 12
DT
▶ ▶
SHIFT
S-VAR
▶ ▶
SHIFT
S-VAR
▶ ▶
SHIFT
S-VAR
▶ ▶ ▶
9
SHIFT
S-VAR
▶ ▶ ▶
4
SHIFT
S-VAR
▶ ▶ ▶
4
SHIFT
S-VAR
59
)
3
)
4
(x
)
1
1
(x
)
2
2
10 , 6
DT
DT
=
1
=
2
=
3
=
3
=
1
=
2
y)
2