Biostatistics Examination -
For Questions 1-9, check the appropriate box. Indicate whether the variable is: Dichotomous, Ordinal, Categorical, or Continuous
Variable (Survey Question)
Q1. Age of first prescription pain pill use (At what age did you first take a prescription pain pill?)
Q2. Race/Ethnicity (What race/ethnicity do you identify with?)
Q3. Zip code (What is your zipcode?)
Q4. Smoking Status (Do you smoke ever, sometimes, float of the times, or always)
Q5. BMI (What is your BMI? kg/m2)
Q6. Marital Status (What is your marital status, single, divorced, married, or widowed?)
Q7. Weight Perception (Do you believe your weight is underweight, normal weight, or overweight?)
Q8. Yearly Income ($) (What is your yearly income?)
Q9. HS Graduation (Did you ever graduate college, yes or no?)
Q10. The following are body mass index (BMI) scores measured in 4 patients who are have been diagnosed with anorexia nervosa and are participating in a study of risk factors for eating disorders. Body mass index is measured as the ratio of weight in kilograms to height in meters squared.
17 16 18 18
a) Compute the mean.
b) Compute the median.
c) Compute the mode.
d) Compute the range.
e) Compute the standard deviation.
f) Determine if there are outliers.
Q11. A national survey is conducted to assess the association between hypertension and stroke in persons over 55 years of age. Development of stroke was monitored over a 5-year follow-up period. The data are summarized below and the numbers are in millions.
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Develop Stroke
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Did not Develop Stroke
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Hypertension
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20
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30
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No Hypertension
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12
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38
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a) Compute the 5-year incidence of stroke in persons over 55 years of age. Use a base of 100 persons.
b) Compute the relative risk of stroke comparing hypertensive to non-hypertensive persons.
c) Compute the odds ratio of stroke comparing hypertensive to non-hypertensive persons.
For Questions 12-16, refer to the following scenario and table:
The relative frequencies of blood lead concentrations for two groups of workers in Canada, one examined in 1979 and the other in 1987 are displayed below:
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Blood lead (μg/dl)
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Frequency (%)
|
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1979
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1987
|
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<20
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11.5
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28.9
|
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20-29
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12.1
|
21.7
|
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30-39
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13.9
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15.8
|
|
40-49
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13.1
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14.9
|
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50-59
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18.8
|
9.3
|
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60-69
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12.8
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6.6
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70-79
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8.4
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1.9
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≥ 80
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9.4
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0.9
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Q12. Compute the cumulative frequencies for each group of workers in 1987. Fill in the last column. You don't have to show your work for this problem.
|
Blood lead (μg/dl)
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1979
|
1987
|
|
Frequency (%)
|
Cumulative Frequency (%)
|
Frequency (%)
|
Cumulative Frequency (%)
|
|
<20
|
11.5
|
11.5
|
28.9
|
|
|
20-29
|
12.1
|
23.6
|
21.7
|
|
|
30-39
|
13.9
|
37.5
|
15.8
|
|
|
40-49
|
13.1
|
50.6
|
14.9
|
|
|
50-59
|
18.8
|
69.4
|
9.3
|
|
|
60-69
|
12.8
|
82.2
|
6.6
|
|
|
70-79
|
8.4
|
90.6
|
1.9
|
|
|
≥ 80
|
9.4
|
100.0
|
0.9
|
|
Q13. The % of workers with blood lead levels between 70-79 μg/dl was greater in what year?
Q14. In 1979, Approximately 50% of the workers had blood lead levels less than what amount?
Q15. In 1987, approximately what percentage of workers had blood lead levels less than or equal to 29µg/dl?
Q16. According to this data, it appears as if the blood lead levels of workers were lower in which year?
For Questions 17-18, refer to the following scenario and figures:
The Observation Survey of Early Literacy Achievement (OS; Clay, 2002) is an individually administered assessment tool that is used extensively in the United States and other countries. The participants in the current study were 182 first-grade students. Of these students, 130 had been identified as being at risk for reading difficulty, and 52 were typically developing readers from the same classrooms.
At the beginning and end of first grade, all students (n = 182) were individually assessed. We administered the OS to the participating first graders in September [the pretest] and early May [the posttest] of the same school year. Figure 1 (attached) presents the score distributions for the 182 students.
Q17. Based on the histograms above, for which one of the above tests is there the most change from pretest to posttest?
Q18. What is the approximate frequency for a score less than 50.0 on the Letter identification post-test? (1 point) (see a larger image of the graph at the end of the exam).
For Question 19-20, refer to the following SPSS output table (attached):
Q19. In reporting this data, is it best to report the median or the mean? The 25th quartile value is 6. Justify your answer.
Q20. In reporting this data, is it best to report the standard deviation or the interquartile range (IQR)?
For questions 21-24, refer to the following histogram (attached):
Q21. What is the sample size?
Q22. In the histogram, are the outliers "far to the left" or "far to the right"?
Q23. How have the outliers influenced the mean?
Q24. What percentage of participants reported less than 2.0 contact hours?
For Questions 25-29, match the term on the right column with the best answer from the left column.
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Q25. The statistic that measures the deviations of the observations from the mean.
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A. s
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Q26. The statistic that describes the difference between the 25th and the 75th percentiles.
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B. Median
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Q27. The most frequent occurring observation.
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C. Range
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Q28. The middle-most observation of ordered data.
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D. Mode
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Q29. The statistic that describes the difference between the highest and the lowest observations.
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E. IQR
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Q30. Which of the following are measures of variation (i.e. dispersion)? (CIRCLE ALL THAT APPLY)
a. Median
b. Mean
c. Standard Deviation
d. IQR
31. Which of the following types of variables are best described using a mean? (CIRCLE ALL THAT APPLY)
a. Categorical
b. Ordinal
c. Continuous
32. Which of the following types of variables are best described using frequencies? (CIRCLE ALL THAT APPLY)
a. Categorical
b. Ordinal
c. Continuous
33. Regardless of whether there are or are not outliers, which of the following statistics should you always report? (CIRCLE ALL THAT APPLY)
a. Variance
h. Range
c. Minimum
d. Maximum
e. Sample Size
34. Which of the following study designs have the least amount of temporal ambiguity (i.e. are longitudinal)? (CIRCLE ALL THAT APPLY)
a. Case-control
b. Randomized Control Trial
c. Cohort
d. Cross-Sectional Study
35. Answer True or False to each of the following:
a) The mean is a better measure of location when there are outliers.
b) The median of a sample is sensitive to extreme values or outliers.
Q36. An investigator wants to test whether exposure to second-hand smoke before 1 year of life is associated with development of childhood asthma (defined as asthma diagnosed before 5 years of age). Give two possible study designs and indicate the pros and cons of each. Then, provide your recommendation for the most efficient design.
Attachment:- Assignment File.rar