Lesson 2: Summarizing Data

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Self-Assessment Quiz

Now that you have read Lesson 2 and have completed the exercises, you should be ready to take the self-assessment quiz. This quiz is designed to help you assess how well you have learned the content of this lesson. You may refer to the lesson text whenever you are unsure of the answer.

Unless instructed otherwise, choose ALL correct answers for each question.

Use Table 2.16 for Questions 1 and 2, and for Questions 10–13.

Table 2.16 Admitting Clinical Characteristics of Patients with Severe Acute Respiratory Syndrome — Singapore, March–May, 2003

ID Date of Diagnosis Sex Age (Years) How Acquired Symptoms† Temp (°C) Lymphocyte Count (× 10 −9/L)‡ Outcome
01 * Female 71 Community F, confusion 38.7 0.78 Survived
02 3/16 Female 43 Community C, D, S, H, F 38.9 0.94 Died
03 3/29 Male 40 HCW C, H, M, F 36.8 0.71 Survived
04 * Female 78 Community D 36.0 1.02 Died
05 * Female 53 Community C, D, F 39.6 0.53 Died
06 4/6 Male 63 Community C, M, F, dizziness 35.1 0.63 Died
07 * Male 84 Inpatient D, F 38.0 0.21 Died
08 * Male 63 Inpatient F 38.5 0.83 Survived
09 * Female 74 Inpatient F 38.0 1.34 Died
10 * Male 72 Inpatient F 38.5 1.04 Survived
11 * Female 28 HCW H, M, F 38.2 0.30 Survived
12 * Female 24 HCW M, F 38.0 0.84 Survived
13 * Female 28 HCW M, F 38.5 1.13 Survived
14 * Male 21 HCW H, M, F 38.8 0.97 Survived

* Date of onset not provided in manuscript

† C=cough, D=dyspnea, F=fever, H=headache, M=myalgia, S=sore throat

‡ Normal > 1.50 × 10 −9/L

¶ HCW = health-care worker

Data Source: Singh K, Hsu L-Y, Villacian JS, Habib A, Fisher D, Tambyah PA. Severe acute respiratory syndrome: lessons from Singapore. Emerg Infect Dis 2003;9:1294–8.

  1. Table 2.16 is an example of a/an _______________________________________ .
  2. For each of the following variables included in Table 2.16, identify if it is:
    • Ordinal
    • Qualitative
    • Quantitative
    • Ratio
    • Categorical
    • Continuous
    • Interval
    • Nominal
    1. ____ Sex
    2. ____ Age
    3. ____ Lymphocyte Count
  3. Which of the following best describes the similarities and differences in the three distributions shown in Figure 2.11?
    Figure 2.11
    Three symmetrical bell curves. Each a different shape.
    Image Description
    1. Same mean, median, mode; different standard deviation
    2. Same mean, median, mode; same standard deviation
    3. Different mean, median, mode; different standard deviation
    4. Different mean, median, mode; same standard deviation
  4. Which of the following terms accurately describe the distribution shown in Figure 2.12?
    Figure 2.12
    A histogram shows a dramatic rise then a gradual decrease.
    Image Description
    1. Negatively skewed
    2. Positively skewed
    3. Skewed to the right
    4. Skewed to the left
    5. Asymmetrical
  5. What is the likely relationship between mean, median, and mode of the distribution shown in Figure 2.12?
    1. Mean < median < mode
    2. Mean = median = mode
    3. Mean > median > mode
    4. Mode < mean and median, but cannot tell relationship between mean and median
  6. The mode is the value that:
    1. Is midway between the lowest and highest value
    2. Occurs most often
    3. Has half the observations below it and half above it
    4. Is statistically closest to all of the values in the distribution
  7. The median is the value that:
    1. Is midway between the lowest and highest value
    2. Occurs most often
    3. Has half the observations below it and half above it
    4. Is statistically closest to all of the values in the distribution
  8. The mean is the value that:
    1. Is midway between the lowest and highest value
    2. Occurs most often
    3. Has half the observations below it and half above it
    4. Is statistically closest to all of the values in the distribution
  9. The geometric mean is the value that:
    1. Is midway between the lowest and highest value on a log scale
    2. Occurs most often on a log scale
    3. Has half the observations below it and half above it on a log scale
    4. Is statistically closest to all of the values in the distribution on a log scale
Use Table 2.16 for Questions 10–13. Note that the sum of the 14 temperatures listed in Table 2.16 is 531.6.
  1. The mode of the temperatures listed in Table 2.16 is:
    1. 37.35°C
    2. 37.9°C
    3. 38.0°C
    4. 38.35°C
    5. 38.5°C
  2. The median of the temperatures listed in Table 2.16 is:
    1. 37.35°C
    2. 37.9°C
    3. 38.0°C
    4. 38.35°C
    5. 38.5°C
  3. The mean of the temperatures listed in Table 2.16 is:
    1. 37.35°C
    2. 37.9°C
    3. 38.0°C
    4. 38.35°C
    5. 38.5°C
  4. The midrange of the temperatures listed in Table 2.16 is:
    1. 37.35°C
    2. 37.9°C
    3. 38.0°C
    4. 38.35°C
    5. 38.5°C
  5. In epidemiology, the measure of central location generally preferred for summarizing skewed data such as incubation periods is the:
    1. Mean
    2. Median
    3. Midrange
    4. Mode
  6. The measure of central location generally preferred for additional statistical analysis is the:
    1. Mean
    2. Median
    3. Midrange
    4. Mode
  7. Which of the following are considered measures of spread?
    1. Interquartile range
    2. Percentile
    3. Range
    4. Standard deviation
  8. The measure of spread most affected by one extreme value is the:
    1. Interquartile range
    2. Range
    3. Standard deviation
    4. Mean
  9. The interquartile range covers what proportion of a distribution?
    1. 25%
    2. 50%
    3. 75%
    4. 100%
  10. The measure of central location most commonly used with the interquartile range is the:
    1. Arithmetic mean
    2. Geometric mean
    3. Median
    4. Midrange
    5. Mode
  11. The measure of central location most commonly used with the standard deviation is the:
    1. Arithmetic mean
    2. Median
    3. Midrange
    4. Mode
  12. The algebraic relationship between the variance and standard deviation is that:
    1. The standard deviation is the square root of the variance
    2. The variance is the square root of the standard deviation
    3. The standard deviation is the variance divided by the square root of n
    4. The variance is the standard deviation divided by the square root of n
  13. Before calculating a standard deviation, one should ensure that:
    1. The data are somewhat normally distributed
    2. The total number of observations is at least 50
    3. The variable is an interval-scale or ratio-scale variable
    4. The calculator or software has a square-root function
  14. Simply by scanning the values in each distribution below, identify the distribution with the largest standard deviation.
    1. 1, 10, 15, 18, 20, 20, 22, 25, 30, 39
    2. 1, 3, 8, 10, 20, 20, 30, 32, 37, 39
    3. 1, 15, 17, 19, 20, 20, 21, 23, 25, 39
    4. 41, 42, 43, 44, 45, 45, 46, 47, 48, 49
  15. Given the area under a normal curve, which two of the following ranges are the same? (Circle the TWO that are the same.)
    1. From the 2.5th percentile to the 97.5th percentile
    2. From the 5th percentile to the 95th percentile
    3. From the 25th percentile to the 75th percentile
    4. From 1 standard deviation below the mean to 1 standard deviation above the mean
    5. From 1.96 standard deviations below the mean to 1.96 standard deviations above the mean
  16. The primary use of the standard error of the mean is in calculating the:
    1. confidence interval
    2. error rate
    3. standard deviation
    4. variance

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