A city wants to know if a new advertising campaign to make citizens aware of the

Question

A city wants to know if a new advertising campaign to make citizens aware of the dangers of driving after drinking has been effective. They count the number of drivers who have been stopped with more alcohol in their systems than the law allows for each day of the week in the week before and the week a month after the campaign starts. Here are the results:

Before: (Monday-Sunday) 5,4,2,4,6,14,6

After: (Monday-Sunday):2,0,2,1,8,7,7

Assume that the number of stops of drunk drivers (before as well as after the campaign) is each normally distributed. Use the following notation:

(d):The mean of the difference in number of daily stops of drunk drivers between those days after and those days before the campaign.

We will be using 10% level of significance when conducting hypothesis testing.

Question 31

Specify the null and alternative hypotheses using correct notations.

Select one:

a. H0: d < 0 Versus Ha: d0

b. H0: d0 Versus Ha: d<0

Question 32: What is the value of the test statistic?

a. -1.67

b. 1.67

c. -1.44

d. 1.44

Question 33: What is the critical value of the test?

a. 1.44

b. -1.44

c. -1.94

d. 1.94

Question 34: Using the critical value approach, what is the correct statistical conclusion?

a. Reject H(0) in favor of H(a)

b. Do not reject H(0)

Question 35: What is the p-value?

a. 0.14529072

b. 0.01

c. 0.07264536

d. 0.05

Question 36: Using the p-value approach, what is the correct statistical conclusion?

a. Reject H(0) in favor of H(a)

b. Do not reject HO

Explanation / Answer

Q.31 The Hypothesises are

Null Hpothesis : H0 :d0 Versus Ha: d<0 [ Option B]

as d =The mean of the difference in number of daily stops of drunk drivers between those days after and those days before the campaign.

Q.32 Test Statistic

t = Xd bar /  (d /sqrt(n)) = -2/(3.162/sqrt(7) = - 1.67

Q.33 tcritical ( alpha = 0.1 and dF = 6, two tailed ) =- 1.943

Q.34

Question 34: Using the critical value approach, what is the correct statistical conclusion?

a. Reject H(0) in favor of H(a)

b. Do not reject H(0)

so obviously as t < tcritical , then we should not reject the null hypothesis.

Q. 35 P - value = 0.1453

Q.36 P- value is greater than significance level so we will not rejct Null hypothesis.

Day Before campaign After Campaign difference Mon 5 2 -3 Tue 4 0 -4 Wed 2 2 0 Thur 4 1 -3 Fri 6 8 2 Sat 14 7 -7 Sun 6 7 1 average 5.857143 3.8571429 -2 std. dev. 3.848314 3.3380918 3.162278

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