F f 2 1 a b 1, Scl), Example 2 – Casio fx-570MS User Manual
Page 33: Y ) n . x σ, Operation
– 30 –
Statistics Problems
Example 2
Example 2
The following table shows the mathematics and English
test results for eight students.
Use this data to determine the correlation coefficient of the test scores.
The correlation coefficient expresses the extent to which
a change in one type of data tends to correspond to a
change in another type of data.
The correlation coefficient
r
for the two types of data
x
and
y
is obtained
using the following expression.
(
x
_
,
y
_
:
x
,
y
mean;
x
σ
n
,
y
σ
n
:
x
,
y
standard deviation)
*The following shows operation using the fx-100MS/115MS/570MS/991MS.
1
.
Enter the REG Mode and select liner regression (Lin).
First, clear statistical memory.
F F 2 1
A B 1
(Scl)
= ]]
2
.
Input the data.
Data items are input in pairs.
Separate each item that makes up a pair with
P , and press S to register the pair.
64
P 80 S 72 P 77 S 85 P 68 S 53 P 84 S
61
P 75 S 86 P 96 S 61 P 68 S 58 P 71 S
3
.
Calculate the correlation coefficient.
A X r r 3
(r)
=
The correlation coefficient of the above data is about 0.259.
Operation
Explanation
Explanation
(
x
i
–
x)
2
.
r = =
i
=
1
n
i
=
1
n
(
y
i
–
y)
2
i
=
1
n
(
x
i
–
x)
(
y
i
–
y)
i
=
1
n
(
x
i
–
x)
(
y
i
–
y)
n.x
σ
n
.y
σ
n
58
M
61
M
86
M
61
M
53
M
85
M
72
M
64
M
71
E
68
E
96
E
75
E
84
E
68
E
77
E
80
E
Math
64
72
85
53
61
86
61
58
English
80
77
68
84
75
96
68
71