In: Statistics and Probability
A study examined parental influence on teenagers' decisions to smoke. A group of students who had never smoked were questioned about their parents' attitudes toward smoking. These students were questioned again two years later to see if they had started smoking. The researchers found that, among the
284
students who indicated that their parents disapproved of kids smoking,
64
had become established smokers. Among the
30
students who initially said their parents were lenient about smoking,
12
became smokers. Do these data provide strong evidence that parental attitude influences teenagers' decisions about smoking? Complete parts a through f.
a) What kind of design did the researchers use?
A retrospective observational study
An experiment
A prospective observational study
b) Write the appropriate hypotheses. Let
p1
be the proportion of teenagers whose parents had indicated disapproval of smoking for them who became smokers themselves. Let
p2
be the proportion of teenagers whose parents had expressed leniency toward smoking for them who became smokers themselves. Choose the correct answer below.
A.
H0:
p1minus
p2not equals
0
HA:
p1minus
p2equals
0
B.
H0:
p1minus
p2equals
0
HA:
p1minus
p2not equals
0
C.
H0:
p1minus
p2equals
0
HA:
p1minus
p2greater than
0
D.
H0:
p1minus
p2greater than
0
HA:
p1minus
p2equals
0
c) Are the assumptions and conditions necessary for inference satisfied?
A.
Yes, all of the assumptions and conditions are satisfied.
B.
No, because the randomization condition is not satisfied.
C.
No, because the 10% condition is not satisfied.
D.
No, because the success/failure condition is not satisfied.
E.
No, because the independent groups assumption is not satisfied.
d) Test the hypothesis and state your conclusion.
Determine the test statistic.
zequals
nothing
(Round to two decimal places as needed.)
Find the P-value.
Pequals
nothing
(Round to four decimal places as needed.)
State your conclusion. Use a significance level of
alpha
equals0.05
.
Choose the correct answer below.
A.
Reject
the null hypothesis. There
is
sufficient evidence that parental attitude influences teenagers' decisions about smoking.
B.
Do not reject
the null hypothesis. There
is not
sufficient evidence that parental attitude influences teenagers' decisions about smoking.
C.
Do not reject
the null hypothesis. There
is
sufficient evidence that parental attitude influences teenagers' decisions about smoking.
D.
Reject
the null hypothesis. There
is not
sufficient evidence that parental attitude influences teenagers' decisions about smoking.
e) Explain in this context what your P-value means. Choose the correct answer below.
A.
If there is no difference in the proportions, there is about a (100P)% chance of seeing the observed difference or larger by natural sampling variation.
B.
There is about a (100P)% chance that there is a difference in the proportions.
C.
There is about a (100P)% chance that there is no difference in the proportions.
D.
If the observed difference is the true difference, then there is about a (100P)% chance that there is no difference in the proportions.
f) If that conclusion is actually wrong, which type of error did you commit?
Type
Upper I
error
Type
II
error