Question

Calculate the correlation coefficient r, letting Row 1 represent the x-values and Row 2 the y-values. Then calculate it again, letting Row 2 represent the x-values and Row 1 the y-values. What effect does switching the variables have on r?

Row 1 |
---|

12

21

38

48

54

66

76

Row 2 |
---|

177

198

194

133

156

117

173

Calculate the correlation coefficient r, letting Row 1 represent the x-values and Row 2 the y-values.

Answer #1

There is negative correlation between variables x and y

Calculate the correlation coefficient, r, for the data
below.
Calculate the correlation coefficient, r, for the data
below.
X= -10 -8 -1 -4 -6 -7 -5 -3 -2 -9
Y= -15 -13 4 -4 -7 -11 -6 -2 1 -13

Variable X and Y have a correlation coefficient of .75.
If you multiple all the values of variable X by 2 and all values of
variable Y by -4, what is your new correlation
coefficient?
A.
r =-.75
B.
r =.75
C.
It cannot be determined without the raw data
D.
r =.25

Calculate the Pearson Product-Moment Correlation Coefficient, r,
for the following data set.
x
y
59
-119
24
-35
50
-107
47
-73
41
-78
72
-117
40
-55
Round your answer to three decimal places.

Calculate the linear correlation r using the table of
values.
x
y
43
10
2
19
99
1
86
2
50
8
A. r = 0.326
B. r = -0.992
C. r = -0.326
D. r = 0.992

HOW WELL CORRELATED ARE THESE VARIABLE? WE MUST CALCULATE THE
CORRELATION COEFFICIENT (r) USING THE SAME (X,Y) DATA POINTS
X
X^2
Y
Y^2
X*Y
4
6
3
7
5
12
11
17
10
10
14
14
SUMS = ∑
47
66
nƩ (X*Y)=
(ƩX) * (ƩY) =
'nƩX^2 =
(ƩX)^2 =
n ƩY^2 =
(ƩY)^2 =
'CORRELATION COEFFICIENT (r) =

Solution 1 of 2 You were asked to calculate the correlation
coefficient, r.
Completion Percentage 55.5 57 58 58.5 59 Interception Percentage
5 4 2.5 2 1.5
To find r, you can use the formula, a scientific calculator, or
statistical software. To use the formula, we should first determine
n, ∑xy, ∑x, ∑y, ∑x2, and ∑y2. Since we have 5 data points, n=5. In
this case our x-values are "Completion Percentage" and our y-values
are "Interception Percentage", so we calculate...

Examine the computation formula for r, the sample
correlation coefficient.
1. In the formula for r, if we exchange the symbols
x and y, do we get a different result or do we
get the same (equivalent) result? Explain your answer.
(A) The result is the same because the formula is not dependent
on the symbols.
(B) The result is different because the formula is not dependent
on the symbols.
(C) The result is different because the formula is dependent...

Examine the computation formula for r, the sample
correlation coefficient.
(a) In the formula for r, if we exchange the symbols
x and y, do we get a different result or do we
get the same (equivalent) result? Explain your answer.
The result is the same because the formula is not dependent on
the symbols.The result is different because the formula is
dependent on the symbols. The result is
different because the formula is not dependent on the symbols.The
result is...

Assuming a linear relationship between X and
Y, if the coefficient of correlation (r) equals
−0.75, this means that:
a.
there is very weak correlation.
b.
the slope b1 is = −0.75.
c.
the value of X is always greater than the value of
Y.
d.
None of these choices are true.
Which of the following is a property of the slope,
b1?
a.
The slope equals one if X and Y have the same
variance.
b.
The slope has...

find coefficient correlation r ?
x
y
1
2.0
3
23.33
2
65.33
4
12.65
5
50
6
60
7
16
8
32.6
10
87.9
9
99.8
21
54.7
11
21.9
13
55.7
14
21.6
15
67.7
16
76.8
17
12.8
18
52.7
18
12.8
16
27.9
15
87.8
80
22.3
54
54.7
54
12.65
21
76.7
42
121
65
65
22
364.66
21
725.7

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