STAT 110 Practice Exam 2
Important: You must use a pencil on this exam. You may write on the exam itself, but not large enough so others can see.
Cover your paper!!! There only 3 items allowed at your seat: writing utensils, drink, sweater/jacket/blanket,. No backpacks,
notebooks, papers, pocketbooks, laptops, etc. and especially no cell phones. Good luck!
1. The portion of a clinical trial that measures the benefits and risks of a drug after FDA approval for market is: A. Phase I B. Phase II C. Phase III D. Phase IV 2. Clinical trials are subject to the scrutiny of an institutional review board. What is the purpose of the institutional review board in a clinical trial? A. determine whether the study will yield statistically sound results B. make sure the study does not go over the federally funded budget C. ensure the patients in the trial have minimal risk for harm Questions 3 – 6 are based on the following description: The measurement of body temperature may be helpful for monitoring whether a person is ill, or whether treatment is working. A high temperature is a fever. The average normal body temperature is 98.6 degrees Fahrenheit. A study evaluated plastic strip thermometers which change color to show the temperature. Though convenient, this method is the less accurate than electronic thermometers. (Source: http://www.nlm.nih.gov/medlineplus/ency/article/003400.htm ) 3. What is the unit of measure? A. Plastic strip thermometer B. 98.6 degrees Fahrenheit C. Degrees Fahrenheit D. Body temperature 4. What is the variable? A. Plastic strip thermometer B. 98.6 degrees Fahrenheit C. Degrees Fahrenheit D. Body temperature 5. If the plastic strip thermometers are consistently subtracting 1.5 degrees Fahrenheit from every person’s reading, then it is a(n) _______________ measuring process. A. unreliable B. biased C. invalid D. unbiased 6. If we take several measurements on the same person and get different results each time (some too high, some too low) we would call this measuring process A. unreliable B. biased C. invalid D. unbiased Questions 7 – 10 are based on the following description/graphic: The following boxplot displays Employee Data from IBM showing SALARY by GENDER. (Source: http://pic.dhe.ibm.com/infocenter/spssstat/v20r0m0/index.jsp?topic=%2Fcom.ibm.spss.statistics.help%2Fgraphboard_creating_examples_boxplot.htm ) 7. The variable SALARY is A. Categorical nominal B. Categorical ordinal C. Quantitative 8. The variable GENDER is A. Categorical nominal B. Categorical ordinal C. Quantitative 9. Which gender has the largest median? A. Female B. Male 10. Which gender has the highest variability? A. Female B. Male Questions 11 – 12 are based on the following description/graphic: 11. This data set is best described as: A. Bimodal B. Symmetric C. Skewed Left D. Skewed Right 12. The mean of this data set is: A. Less than the median B. Approximately equal to the median C. Greater than the median D. Can’t tell from the picture Questions 13 – 14 are based on the following description/table: A public health nurse has a caseload of 50 families. The following shows the distribution of the number of children per family for this population. (Source: Daniel, Wayne W., Biostatistics: A Foundation for Analysis in the Health Sciences, Fourth Edition, 1987, John Wiley & Sons, Inc., p. 66) Number of Children per Family in a Population of 50 Families
Column a: 13. Column b is the: Column b Column c
# children A. Frequency B. Relative Frequency 0
2 0.04
C. Variable 1
4 0.08
2
7 0.14
3
6 0.12
14. An appropriate graphic to illustrate these data 4
8 0.16
would be: 5
10 0.20
A. Pictogram 6
9 0.18
B. Line graph 8 4 0.08
C. Bar chart 15. Which of the following statements is/are true? A. In a symmetric distribution, one should report the median and the standard deviation B. In a skewed distribution, one should report the median as part of the 5‐number summary C. In a symmetric distribution, one should report the mean and the standard deviation D. In a skewed distribution, one should report the mean as part of the 5‐number summary E. B and C are both true Questions 16 – 18 are based on the following data set: 8 10 10 1 5 7 2 6 5 3 16. The median is: A. 7 B. 6 C. 5.5 D. 5 17. The first quartile (Q1) is: A. 2 B. 3 C. 8 D. 9 18. Which of the following statements is true concerning the mode of the data set? A. The mode cannot be determined. B. There are two modes; that is, the data set is bimodal. C. The mode is 7 since it is close to the middle of the data set. D. There is exactly one mode for the data set; it is 5. 19. An advanced physics class typically has about 80% of its students who did very well in the prerequisite course and get ok exam grades, and 20% of its students who did very poorly in the prerequisite course and get very low exam grades. If the professor wants to scare off the weaker students before registration next semester, he should report: A. The mean of the student grades B. The median of the student grades C. Both the mean and median will be approximately the same, so it shouldn’t make a difference 20. Heights of a group of women that are approximately normally distributed with a mean of 65 inches and a standard deviation of 2.5 inches. At what percentile would someone who was 67.5 inches tall be? A.
B.
C.
D.
E.
16th percentile 32nd percentile 34th percentile 68th percentile 84th percentile Questions 21 ‐ 25 are based on the following description: The length of life of an instrument produced by a
machine has a normal distribution with a
mean of 12 months and
standard deviation of 2 months.
(Source:
http://www.analyzemath.com/statistics/normal_distribution.html )
21.
To be acceptable for quality control, the length of
life of the instrument must be at least 8 months. What is the probability that the length of life will be less than 8
months?
A.
B.
C.
D.
22.
What is the probability that the length of life of the instrument will be between 10 and 14 months?
A.
B.
C.
D.
23.
99.7%
-3.00
1.00
3.00
What proportion of the instrument lengths of life will be within 2 standard deviations of the mean?
A.
B.
C.
D.
25.
0.05 (5%)
0.025 (2.5%)
0.68 (68%)
0.95 (95%)
Compute the standard score (z-score) for a length of life of 18 months.
A.
B.
C.
D.
24.
0.025 (2.5%)
0.95 (95%)
0.05 (5%)
0.68 (68%)
0.997 (99.7%)
0.95 (95%)
0.475 (47.5%)
1.00 (100%)
If the instrument lengths of life were more spread out, the standard deviation would be:
A.
B.
C.
D.
lower
the same
higher
can’t be determined from the available data