7
Copyright © Lexibook 007
ENGLISH
Power Regression:
We suspect that x and y are connected by an equation of the type y=A x
B
and we try to confirm this hypothesis as follows:
x
0,5
1
1,5
2
y
1,4
2
2,4
2,9
We switch to the two-variable statistics mode and Pwr regression:
[MODE] 3 [ ] 1
->
Pwr
is displayed
[SHIFT][CLR] 1 [=]
-> Clear
Beginning of data input:
[.] 5 [,] 1 [.] 4 [DT]
1 [,] 2 [DT] … etc.
[SHIFT] [S-SUM] 3 [=] -> n | 4.
We obtain the following values for A, B and r:
[SHIFT] [S-VAR] [ ][ ] 1 [=]
-> A | 1.994142059
[SHIFT] [S-VAR] [ ][ ] 2 [=]
-> B | 0.515317442
[SHIFT] [S-VAR] [ ][ ] 3 [=]
-> r | 0.998473288
The power regression is confirmed because r=0,998.
We can therefore estimate that y ≈ 2x
1/2
= 2√x.
4 [SHIFT] [S-VAR] [ ][ ][ ] 2 [=] -> 4 | 4.073878837
6 [SHIFT] [S-VAR] [ ][ ][ ] 1 [=] -> 6 | 8.479112672
Quadratic Regression:
We suspect that x and y are connected by an equation of the type
y= A+Bx+Cx
and we try to confirm this hypothesis as follows:
We switch to the two-variable statistics mode and quadratic regression:
[MODE] 3 [ ] 3
->
Quad
is displayed
[SHIFT] [CLR] 1 [=]
-> clear
Beginning of data input :
29 [,] 1 [.] 6 [DT]
50 [,] 23[.]5 [DT] … etc.
[SHIFT] [S-SUM] 3 [=]
-> n | 5.
We obtain the following values for A, B, and C:
[SHIFT] [S-VAR] [ ][ ] 1 [=] -> A | -35.59856934
[SHIFT] [S-VAR] [ ][ ] 2 [=] -> B | 1.495939413
[SHIFT] [S-VAR] [ ][ ] 3 [=] -> C | -6.71629667-03
For x= 16 we obtain only one estimated value for y:
16 [SHIFT] [S-VAR] [ ][ ][ ] 3 [=]
-> 16
| -13.38291067
Yet for y=20 we obtain two possible values for x:
20 [SHIFT] [S-VAR] [ ][ ][ ] 1 [=]
-> 20
1
| 47.14556728
20 [SHIFT] [S-VAR] [ ][ ][ ] 2 [=]
-> 20
| 175.5872105
If the value of y put forward does not have a real x solution, for example
y=56, your calculator will display Math ERROR.
y^
x
29
50
74
103
118
y
1,6
23,5
38
46,4
48
y^
x^
y^
x^
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