Question

We want to know whether the proportion of U.S. children living in families with
combined incomes below the poverty line has changed in the last 20 years. In 2000 the
proportion of children living below the poverty line was 12%. Out of a recent random
sample of 90 children 9 were from families with combined incomes below the poverty
line. Use this information to answer the following.
The alternative hypothesis for the above would be
A. ☐μ = 12%
B. ☐μ ≠ 12%
C. ☐π= .12
D. ☐π < .10
E. ☐π ≠ .12
The two tailed .05 critical value for a test of the above would be
A. ☐+/- 1.96
B. ☐+/- 1.645
C. ☐+/- 1.987
D. ☐+/- 1.671
E. ☐none of the above
Calculate p  for use in the above problem situation (rounded to 3 decimal places)
A. ☐.02
B. ☐.10
C. ☐.034
D. ☐.001
E. ☐.095
Your sample proportion =
A. ☐9%
B. ☐.90
C. ☐.12
D. ☐.133
E. ☐.10
I know it doesn’t, but if we assume that your sample data yielded a test statistic=.99,
what would be the exact (use our normal curve table) two tailed p value of your
finding?
A. ☐.3389
B. ☐.1611
C. ☐.3222
D. ☐.05
E. ☐.6778
If you do not reject the null in the above problem, you would say
A. ☐The proportion of children living below the poverty line is still 12%
B. ☐The proportion of children living below the poverty line has gone down
C. ☐The proportion of children living below the poverty line has changed
D. ☐You cannot prove that the proportion of children living below the poverty line
Cohen’s has changed
E. ☐The proportion of children living below the poverty line has not changed at all
Suppose you rejected the null in a hypothesis test to determine if a medicine worked
better than a placebo in controlling symptoms of the common cold and reported
Cohen’s d=.01 That should tell you which of the following
A. ☐ The difference was not statistically significant
B. ☐ The difference was significant using alpha=.01
C. ☐The difference was significant, and the medicine made a big difference in
symptoms
D. ☐The difference was not significant using alpha=.01
E. ☐The difference was significant, but the medicine did not make a big difference
in symptoms.

Answer 1

Sol:

Ho:p=0.12

Ha:p not =0.12

The alternative hypothesis for the above would be

E. ☐π ≠ .12

The two tailed .05 critical value for a test of the above would be

A. ☐+/- 1.96

Calculate p  for use in the above problem situation (rounded to 3 decimal places)

Se=sqrt(p*(1-p)/n)

sqrt(0.12*(1-0.12)/90)

= 0.03425395

0.034

ANSWER:

0.034

Your sample proportion =p^=x/n=9/90=0.1

E. ☐.10

I know it doesn’t, but if we assume that your sample data yielded a test statistic=.99,
what would be the exact (use our normal curve table) two tailed p value of your
finding?

2*left tail

left tail p value ine xcel

==NORMSDIST(-0.99)

=0.161087

=2*0.161087

=0.3222

C. ☐.3222

If you do not reject the null in the above problem, you would say

Rejected Null hypothesis

The proportion of children living below the poverty line is still 12%

effect size=0.01

difference not significant

A. ☐ The difference was not statistically significant