Question

In: Statistics and Probability

# Variable X Variable Y 1 205 1500 2 70 750 3 199 1500 4 151...

#

Variable
X

Variable
Y

1

205

1500

2

70

750

3

199

1500

4

151

1250

5

181

1250

6

217

1250

7

94

1000

8

298

2000

9

135

1000

10

211

1500

11

116

1250

12

72

500

13

82

500

14

206

1500

15

245

2000

16

219

1500

17

63

750

18

200

1500

19

151

1250

20

44

500

What is the significance of the slope. Use a significance level of 0.05

What is the coefficient of determination

Solutions

Expert Solution

X Y X*Y X2 Y2
205.00 1,500.00 3,07,500.00 42,025.00 22,50,000.00
70.00 750.00 52,500.00 4,900.00 5,62,500.00
199.00 1,500.00 2,98,500.00 39,601.00 22,50,000.00
151.00 1,250.00 1,88,750.00 22,801.00 15,62,500.00
181.00 1,250.00 2,26,250.00 32,761.00 15,62,500.00
217.00 1,250.00 2,71,250.00 47,089.00 15,62,500.00
94.00 1,000.00 94,000.00 8,836.00 10,00,000.00
298.00 2,000.00 5,96,000.00 88,804.00 40,00,000.00
135.00 1,000.00 1,35,000.00 18,225.00 10,00,000.00
211.00 1,500.00 3,16,500.00 44,521.00 22,50,000.00
116.00 1,250.00 1,45,000.00 13,456.00 15,62,500.00
72.00 500.00 36,000.00 5,184.00 2,50,000.00
82.00 500.00 41,000.00 6,724.00 2,50,000.00
206.00 1,500.00 3,09,000.00 42,436.00 22,50,000.00
245.00 2,000.00 4,90,000.00 60,025.00 40,00,000.00
219.00 1,500.00 3,28,500.00 47,961.00 22,50,000.00
63.00 750.00 47,250.00 3,969.00 5,62,500.00
200.00 1,500.00 3,00,000.00 40,000.00 22,50,000.00
151.00 1,250.00 1,88,750.00 22,801.00 15,62,500.00
44.00 500.00 22,000.00 1,936.00 2,50,000.00
3,159.00 24,250.00 43,93,750.00 5,94,055.00 3,31,87,500.00
CORRELATION

Based on the above table, the following is calculated:

Therefore, based on this information, the sample correlation coefficient is computed as follows:

Correlation Significance Check
Let ρ = population correlation coefficient (unknown)
r = sample correlation coefficient (known; calculated from sample data)

Null and Alternative hypothesis:
H0​:ρ=0 i.e. population correlation coefficient is 'close to 0'
HA​:ρ≠0 i.e. population correlation coefficient is 'significantly different from 0'

Value of correlation coefficient:
r=0.9393

Degrees of freedom
The sample size is n=20, so then the number of degrees of freedom is df = n-2 = 20 - 2 = 18

                                                           Table of Critical Values Method
Critical region:
The corresponding critical correlation value rc​ for a significance level of α=0.05, for a Two-tailed test is: rc=0.4438

Rejection Region
Observe that in this case, the null hypothesis H0​:ρ=0 is rejected if |r|>rc=0.4438.

Decision about the null hypothesis
Based on the sample correlation provided, we have that |r|=0.9393>rc​=0.4438, from which is concluded that the null hypothesis is rejected.

                                                                  T-statistic Method
Test statistic:
The value of the test statistic is calculated using the following formula:

Decision about the null hypothesis:
Since it is observed that |t|=11.6138 > tc​=2.1009, it is then concluded that the null hypothesis is rejected.

The p-value is 0
Using the P-value approach: The p-value is p=0, and since p=0≤0.05, it is concluded that the null hypothesis is rejected.

Conclusion
It is concluded that the null hypothesis Ho is rejected. Therefore, there is enough evidence to claim that the correlation coefficient is different than 0, at the 0.05 significance level.

Coefficient of determination


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