Question

A number of minor automobile accidents occur at various high-risk intersections despite traffic lights. The traffic department claims that a modification in the type of light will reduce these accidents. The traffic commissioners have agreed to a proposed experiment. Eight intersections were chosen at random, and the lights at those intersections were modified. The numbers of minor accidents during a six-month period before and after the modifications were as follows:

	Number of Accidents
	A	B	C	D	E	F	G	H
Before modification	6	6	8	8	6	8	9	4
After modification	6	7	3	7	2	1	2	8

At the 0.1 significance level, is it reasonable to conclude that the modification reduced the number of traffic accidents?

a. State the decision rule. (Negative answer should be indicated by a minus sign. Round the final answer to 3 decimal places.)

Reject H₀ if t <  .

b. Compute the value of the test statistic. (Negative answer should be indicated by a minus sign. Round the final answer to 3 decimal places.).

The test statistic is  .

c. What is your decision regarding the null hypothesis?

Decision:  (Click to select)  Reject  Do not reject  H₀. There is  (Click to select)  enough  not enough  evidence to reject H₀. The mean number of accidents  (Click to select)  has been  has not been  reduced.

d. What is the p-value? (Round the final answer to 4 decimal places.)

Answer 1

from above:

a)

Decision rule: reject Ho if test statistic t<-1.415

b)

test statistic t =-1.680

c)Reject  H₀. There is enough  evidence to reject H₀.   The mean number of accidents has been reduced

d)

p value =0.0684