In: Statistics and Probability
Here is a bivariate data set.
x | y |
---|---|
70.9 | 24.2 |
46 | 21.3 |
44.4 | 20.8 |
57.6 | 23.4 |
76.5 | 25.4 |
52.3 | 20 |
Find the correlation coefficient and report it accurate to three
decimal places.
r =
What proportion of the variation in y can be explained by
the variation in the values of x? Report answer as a
percentage accurate to one decimal place.
r² = %
x | y |
70.9 46 44.4 57.6 76.5 52.3 |
24.2 21.3 20.8 23.4 25.4 20 |
X - Mx | Y - My | (X - Mx)2 | (Y - My)2 | (X - Mx)(Y - My) |
12.950 Mx: 57.950 |
1.683 My: 22.517 |
167.703 Sum: 870.255 |
2.834 Sum: 22.688 |
21.799 Sum: 126.995 |
Key
X: X Values
Y: Y Values
Mx: Mean of X Values
My: Mean of Y Values
X - Mx & Y -
My: Deviation scores
(X - Mx)2 & (Y -
My)2: Deviation
Squared
(X - Mx)(Y -
My): Product of Deviation Scores
Result Details & Calculation
X Values
∑ = 347.7
Mean = 57.95
∑(X - Mx)2 = SSx = 870.255
Y Values
∑ = 135.1
Mean = 22.517
∑(Y - My)2 = SSy = 22.688
X and Y Combined
N = 6
∑(X - Mx)(Y - My) = 126.995
R Calculation
r = ∑((X - My)(Y - Mx)) /
√((SSx)(SSy))
r = 126.995 / √((870.255)(22.688)) = 0.9038
correlatio coefficient(r) = 0.904
the coefficient of determination(r2) = 0.8169.
which means,
81.7% proportion of the variation in y explained by the variation in the values of x
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