In: Statistics and Probability
Consider the following bivariate data.
Point | A | B | C | D | E | F | G | H | I | J |
x | 0 | 1 | 1 | 2 | 3 | 4 | 5 | 6 | 6 | 7 |
y | 5 | 5 | 6 | 5 | 4 | 3 | 2 | 0 | 1 | 1 |
(a) Construct a scatter diagram of the given bivariate data. (Do
this on paper. Your instructor may ask you to turn in this
work.)
(b) Calculate the covariance. (Give your answer correct to two
decimal places.)
(c) Calculate sx and sy.
(Give your answers correct to three decimal places.)
sx | = |
sy | = |
(d) Calculate r using formula 13.2. (Give your answer
correct to two decimal places.)
(e) Calculate r using formula 13.3. (Give your answer
correct to two decimal places.)
a)
b)
S.No | X | Y | (x-x̅)2 | (y-y̅)2 | (x-x̅)(y-y̅) |
1 | 0 | 5 | 12.2500 | 3.24 | -6.3000 |
2 | 1 | 5 | 6.2500 | 3.24 | -4.5000 |
3 | 1 | 6 | 6.2500 | 7.84 | -7.0000 |
4 | 2 | 5 | 2.2500 | 3.24 | -2.7000 |
5 | 3 | 4 | 0.2500 | 0.64 | -0.4000 |
6 | 4 | 3 | 0.2500 | 0.04 | -0.1000 |
7 | 5 | 2 | 2.2500 | 1.44 | -1.8000 |
8 | 6 | 0 | 6.2500 | 10.24 | -8.0000 |
9 | 6 | 1 | 6.2500 | 4.84 | -5.5000 |
10 | 7 | 1 | 12.2500 | 4.84 | -7.7000 |
Total | 35 | 32 | 54.5000 | 39.60 | -44.0000 |
Mean | 3.500 | 3.20 | SSX | SSY | SXY |
Cov(x,y)=Ssxy/(n-1)= | -4.90 |
c)
sx =2.461
sy = 2.098
d)
correlation coefficient r= | Sxy/(√Sxx*Syy) = | -0.95 |
e_)
r =Cov(x,y)/(sx*sy) = -0.95