Question

You may need to use the appropriate technology to answer this question. A survey was conducted to determine whether hours of sleep per night are independent of age. A sample of individuals was asked to indicate the number of hours of sleep per night with categorical options: fewer than 6 hours, 6 to 6.9 hours, 7 to 7.9 hours, and 8 hours or more. Later in the survey, the individuals were asked to indicate their age with categorical options: age 39 or younger and age 40 or older. Sample data follow. Hours of Sleep Age Group 39 or younger 40 or older Fewer than 6 36 34 6 to 6.9 60 57 7 to 7.9 79 77 8 or more 65 92 (a) Conduct a test of independence to determine whether hours of sleep are independent of age. State the null and alternative hypotheses. H0: Hours of sleep per night is independent of age. Ha: Hours of sleep per night is not independent of age. H0: The proportion of people who get 8 or more hours of sleep per night is not equal across the two age groups. Ha: The proportion of people who get 8 or more hours of sleep per night is equal across the two age groups. H0: Hours of sleep per night is not independent of age. Ha: Hours of sleep per night is independent of age. H0: Hours of sleep per night is mutually exclusive from age. Ha: Hours of sleep per night is not mutually exclusive from age. Correct: Your answer is correct. Find the value of the test statistic. (Round your answer to three decimal places.) What is the p-value

Answer 1

1) The null and alternative hypotheses.

H0: Hours of sleep per night is independent of age.

Ha: Hours of sleep per night is not independent of age.

Test Statistics χ²=4.009

The corresponding p-value for the test at χ²= 4.009 is 0.2604

Explanation:

1) The null and alternative hypotheses.

H0: Hours of sleep per night is independent of age.

Ha: Hours of sleep per night is not independent of age.

2) The data is

≤ 39 ≥ 40 Total

6 hours 36 34 70

6.9-7 hours 60 57 117

7- 7.9 hours 79 77 156

8 hours or more 65 92 157

Total 240 260 500

3) The expected values are computed as follows

260×70/500=36.4

240×117/500 =56.16

260×117/500 =60.84

240×156/500 =74.88

260×156/500 =81.12

240×157/500=75.36

260×157/500 =81.64

4) The squared distances are calculated as

{(36 - 33.6)^2}/{ 33.6} = 0.171

{(34 - 36.4)^2}{ 36.4} = 0.158

{(60 - 56.16)^2}/{ 56.16} = 0.263

{(57 - 60.84)^2}/{ 60.84} = 0.242

{(79 - 74.88)^2}/{ 74.88} = 0.227

{(77 - 81.12)^2}/{ 81.12} = 0.209

{(65 - 75.36)^2}/{ 75.36} = 1.424

{(92 - 81.64)^2}{ 81.64} = 1.315

5) The significance level is set at α=0.05 for df = (4 - 1) (2 - 1) =3

degrees of freedom.

6) The critical region for this test is χ² = χ² >7.815

7) Test Statistics

χ²=i=∑(O ij −Eij )2/Eij

=0.171+0.263+0.227+1.424+0.158+0.242+0.209+1.315

= 4.009

8) Conclusion

As the calculated value χ² =4.009 does not lie in the critical region ≤χ² =7.815, null hypothesis is not rejected.

Therefore, we conclude that there is not enough evidence to accept the alternate hypothesis , at the α=0.05 significance level.

The p-value for the test at χ²= 4.009 is 0.2604