1.If the probability of Caesarean birth is 0.30, and 140 in a sample of 500 births are Caesarean, which of these numbers is n?
A) 0.30
B) 140
C) 500
D) 140/500
2. Online interviews of 1500 parents with children under the age of eight found the proportion who read to their children at least 20 minutes a day to be 0.78. Suppose a reporter would like to claim that more than three-fourths (0.75) of all parents with children under eight read to them at least twenty minutes daily.
What notation is used for the number 0.75?
A) p
B) p^
C) p0
D) None of the above
3. A Type I Error is rejecting the null hypothesis, even though it is true; a Type II Error is failing to reject the null hypothesis, even though it is false.
Merck developed an AIDS vaccine that showed promise in initial tests. Unfortunately, in a subsequent test conducted internationally on a large group of volunteers, those vaccinated were no less likely to become infected than those who were not vaccinated. Apparently, Merck's conclusion in the initial tests was
A) a Type I Error
B) a Type II Error
C) both (a) and (b)
D) neither (a) nor (b)
4. Each student in a class of 80 rolls 8 dice in order to perform inference about the mean of all dice rolls (which happens to be 3.5).
Suppose each student uses his or her sample to test the true null hypothesis that the population mean is 3.5 against the two-sided alternative. About how many of these 80 tests should reject at the α=0.05 level?
A) 0
B) 4
C) 8
D) 28
E) 52
5. Students compared tuition, in thousands of dollars, for samples of public and private colleges/universities in the US.
N Mean St. DevSEMean
Public 5 7.26 1.48 0.66
Private 6 32.32 3.30 1.3
Difference = μ public - μ private
Estimate for differences: -25.06
T-Test of difference =0 (vs. not =): T-Value = XXXX P-Value = 0.000 DF=7
A) Paired study
B) Two-sample study
C) Both of the above
D) None of the above
6. A sleep-lab study found that a group of subjects with a mean age of about 68 years slept significantly less than the group of subjects with a mean age of 22 years, with the former averaging only 7.4 hours and the latter 8.9 hours. In contrast, an ANOVA procedure on student survey data found no significant difference in hours slept among 1st, 2nd, 3rd, and 4th year students. In general, to produce evidence of a relationship between sleep and age, which is more helpful?
A) include individuals who are all roughly the same age
B) include individuals spanning a wide range of ages
C) it doesn't matter how similar or different the ages are
7. You are a researcher, and have set up a hypothesis test of μ. You want to compare the value of the sample mean to the value of the population mean as stated in the null hypothesis. This comparison is accomplished using the test statistic:
A) Z-test
B) F-test
C) Chi-square
8. When would you use a t-statistic vs. a z-statistic?
A) when the standard deviation is known and the sample population is normally distributed
B) when the sample population is normally distributed
C) Both a & b
D) None of the above