Nokea
The measure of central location generally preferred for additional statistical analysis is the:
- A. Mean
- B. Median
- C. Midrange
- D. Mode
Correct Answer: A
Rationale: The mean is used in further computations due to its mathematical properties.
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Contrast the changes in death rates due to cancer, heart disease, and cerebrovascular diseases.
- A. Heart disease and cancer rates increased initially but stabilized or declined, while cerebrovascular diseases declined steadily.
- B. All three diseases showed consistent declines.
- C. Cancer rates increased, while heart disease and cerebrovascular diseases decreased.
- D. Heart disease rates increased, while cancer and cerebrovascular diseases decreased.
Correct Answer: A
Rationale: Heart disease and cancer initially rose but later stabilized or declined, while cerebrovascular diseases showed steady declines due to improved treatments and risk factor management.
A follow-up study was conducted of 3,000 military troops deployed at an atomic test site in Nevada to detect the occurrence of leukemia. A total of 1,870 persons were successfully traced by the investigators, and an additional 443 contacted the investigators on their own as a result of publicity about the study. Four cases of leukemia occurred among the 1,870 individuals traced by the investigators, and an additional four occurred among those individuals who contacted the investigators on their own. Could interpretation of the study results be subject to bias?
- A. Yes, due to differential participation rates between the traced group and self-referrals.
- B. No, because the number of leukemia cases is evenly distributed.
- C. Yes, but only if the traced group had higher radiation exposure.
- D. No, because the study design accounts for all possible biases.
Correct Answer: A
Rationale: Differential participation can lead to selection bias, especially if the characteristics of those who self-refer differ systematically from those traced by investigators.
The best measure of association to use for these data is a/an:
- A. Food-specific attack rate
- B. Odds ratio
- C. Rate ratio
- D. Risk ratio
Correct Answer: B
Rationale: Odds ratios are appropriate for case-control studies.
The vector responsible for leishmaniasis is:
- A. mosquito
- B. bugs
- C. tsetse flies
- D. sandflies
Correct Answer: D
Rationale: Sandflies are the vectors responsible for transmitting leishmaniasis.
The dose of toxin that is lethal to half of the population is known as..
- A. LD50
- B. L50
- C. D50
- D. LD
Correct Answer: A
Rationale: LD50 refers to the lethal dose required to kill 50% of a population, commonly used in toxicology studies.