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Describe the overall trends reflected in the chart.
- A. Cyclical increases followed by declines
- B. Steady increase over time
- C. Steady decline over time
- D. Random fluctuations with no pattern
Correct Answer: A
Rationale: Pertussis exhibits cyclical patterns due to waning immunity and vaccination coverage.
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The statistical analysis of two unrelated big data (n=200) is by:
- A. A paired t-test
- B. Chi-square test
- C. Z-test
- D. Unpaired test
Correct Answer: D
Rationale: Unpaired tests compare means between two independent large samples.
Denominator of prenatal mortality is
- A. Number of live births
- B. Number of deliveries (live and still births)
- C. Live births— still births
- D. Number of still births
Correct Answer: B
Rationale: Prenatal mortality includes both live and still births, making the total number of deliveries the appropriate denominator.
What do vital statistics provide important sources of data on?
- A. Morbidity.
- B. Mortality.
- C. Health-related behaviors.
- D. Injury and disability.
Correct Answer: D
Rationale: Vital statistics also track injuries and disabilities, contributing to a comprehensive health overview.
Which of the following are considered measures of spread?
- A. Interquartile range
- B. Percentile
- C. Range
- D. Standard deviation
Correct Answer: A
Rationale: The interquartile range is a robust measure of variability.
You are conducting a study of insulin resistance and its relationship to body weight. Using a weight scale as your instrument to measure body weight, you find the scale always reads 30 kg regardless of who is standing on it. Discuss the validity and reliability of the scale.
- A. The scale is reliable but not valid.
- B. The scale is neither reliable nor valid.
- C. The scale is valid but not reliable.
- D. The scale is both reliable and valid.
Correct Answer: A
Rationale: Reliability refers to consistency of the measurement, which this scale demonstrates by consistently reading 30 kg. However, validity refers to accuracy, which this scale lacks since it does not measure true weight.