CPH Exam Practice Questions
The lengths of stay for six patients were 0, 0, 1, 2, 2, and 16 days. Which is (are) the best measure(s) to
summarize these data?
A) Mean
B) Median
C) Median and SD
D) Mean and SD
E) Median and Range - correct answer ✔✔E) Median and Range
An epidemiologist attempts to predict the weight of an elderly person from demispan. She randomly
chooses 70 elderly subjects in a particular geographic area and records their weight and demispan
measurements in the form of (x i , y i ) for i = 1...70. Given that the value of the Pearson correlation
coefficient is zero, what can be deduced?
1) There is no relation between weight and demispan
B) There is an almost perfect relationship between weight and demispan
C) There could be some nonlinear relationship between weight and demispan
D) There is a strong negative relationship between weight and demispan
E) All pairs of values of weight and demispan are practically identical - correct answer ✔✔C) There could
be some nonlinear relationship between weight and demispan
Which of the following statistical tests is NOT considered a nonparametric test?
A) Kruskal-Wallis Test
B) Wilcoxon's rank-sum test
C) Tukey's test
D) Mann-Whitney test - correct answer ✔✔C) Tukey's test
,A researcher is designing a new questionnaire to examine patient stress levels on a scale of 0 to 5. What
type of outcome variable is being collected?
A) Ratio
B) Nominal
C) Interval
D) Ordinal
E) Binary - correct answer ✔✔B) Ordinal
In simple linear regression, what is a method of determining the slope and intercept of the best-fitting
line?
A) Least squares
B) R-square
C) Minimum error
D) Least Error
E) Regression - correct answer ✔✔A) Least Squares
The sensitivity of a particular screening test for a disease is 95%, and the specificity is 90%. Which of the
following statements is most correct?
(A) Of 100 people sampled from a population with the disease, the test will correctly detect 95
individuals as positive for the disease
(B) Of 100 people sampled from a population with the disease, the test will correctly detect 90
individuals
(C) If a person tests positive, the probability of having the disease is 0.95
(D) If a person has the disease, there is a 5% chance that the test will be negative
(E) If a person does not have the disease, there is a 5% chance that the test will be positive - correct
answer ✔✔A) Of 100 people samples from a population with the disease, the test will correctly detect
95 individuals as positive for the disease.
,Sensitivity is the proportion of truly diseased people in the screened population who are identified as
diseased by the screening test. It is a measure of the probability of correctly diagnosing a case or the
probability that any given case will be identified by the test (e.g., true positives). Specificity is the
proportion of truly non-diseased people who are so identified by the screening test. It is a measure of
the probability of correctly identifying a nondiseased person with the screening test (e.g., true
negatives).
The Central Limit Theorem states that:
A) The sample mean is unbiased
B) The sample mean is approximately normal
C) The parent population of the sample distribution is normally distributed
D) The sample SD is approximately normal
E) Both statements A) and C) can be deduced from the Central Limit Theorem - correct answer ✔✔B)
The sample mean is approximately normal
The Central Limit Theorem states that if the sample size is large enough, the distribution of the
sample means can be approximated by a normal distribution, even if the original population is not
normally distributed. In other words, the distribution of the sample means approaches a normal
distribution as the sample size increases
Assume that a researcher has measured weight in a sample of 100 overweight adults before and after a
diet and exercise program conducted at the local health department's weekly Eat Health - Be Fit
community program.
To determine whether the mean weight decreased six weeks after the exercise program compared to the
initial baseline measures, the researcher should:
A) Compute the correlation coefficient, r, and determine the association between being overweight and
the community program
B) Conduct a t-test for independent samples
C) Conduct a t-test for dependent samples
, D) Conduct a chi-square test for association
E) Not estimate the decrease because there was no control group for the program - correct answer
✔✔C) Conduct a t-test for dependent samples
A t-test is a hypothesis test to compare population means and proportions. In this case, the sample is
dependent because the tests are performed on the same individuals in the sample.
Which of the following estimates of an odds ratio most strongly suggests a computational error?
1) 7.8
2) 1.2
3) -0.9
4) 20.9 - correct answer ✔✔3) -0.9
An odds ratio of -0.9 most strongly indicates a computational error because an odds ratio is calculated
using probabilities, which cannot be negative.
An odds ratio is the probability that an event will occur divided by the probability that it will not occur.
Since probabilities cannot be negative, a negative odds ratio would indicate computational error.
Which measure of mortality would you calculate to determine the proportion of all deaths that is caused
by heart disease?
A) Case Fatality Ratio
B) Randomized Clinical Trial
C) Crude Mortality Rate
D) Proportional Mortality Ratio - correct answer ✔✔D) Proportional Mortality Ratio
the proportion of deaths in a particular population over a specified period of time attributable to a
specific disease
The lengths of stay for six patients were 0, 0, 1, 2, 2, and 16 days. Which is (are) the best measure(s) to
summarize these data?
A) Mean
B) Median
C) Median and SD
D) Mean and SD
E) Median and Range - correct answer ✔✔E) Median and Range
An epidemiologist attempts to predict the weight of an elderly person from demispan. She randomly
chooses 70 elderly subjects in a particular geographic area and records their weight and demispan
measurements in the form of (x i , y i ) for i = 1...70. Given that the value of the Pearson correlation
coefficient is zero, what can be deduced?
1) There is no relation between weight and demispan
B) There is an almost perfect relationship between weight and demispan
C) There could be some nonlinear relationship between weight and demispan
D) There is a strong negative relationship between weight and demispan
E) All pairs of values of weight and demispan are practically identical - correct answer ✔✔C) There could
be some nonlinear relationship between weight and demispan
Which of the following statistical tests is NOT considered a nonparametric test?
A) Kruskal-Wallis Test
B) Wilcoxon's rank-sum test
C) Tukey's test
D) Mann-Whitney test - correct answer ✔✔C) Tukey's test
,A researcher is designing a new questionnaire to examine patient stress levels on a scale of 0 to 5. What
type of outcome variable is being collected?
A) Ratio
B) Nominal
C) Interval
D) Ordinal
E) Binary - correct answer ✔✔B) Ordinal
In simple linear regression, what is a method of determining the slope and intercept of the best-fitting
line?
A) Least squares
B) R-square
C) Minimum error
D) Least Error
E) Regression - correct answer ✔✔A) Least Squares
The sensitivity of a particular screening test for a disease is 95%, and the specificity is 90%. Which of the
following statements is most correct?
(A) Of 100 people sampled from a population with the disease, the test will correctly detect 95
individuals as positive for the disease
(B) Of 100 people sampled from a population with the disease, the test will correctly detect 90
individuals
(C) If a person tests positive, the probability of having the disease is 0.95
(D) If a person has the disease, there is a 5% chance that the test will be negative
(E) If a person does not have the disease, there is a 5% chance that the test will be positive - correct
answer ✔✔A) Of 100 people samples from a population with the disease, the test will correctly detect
95 individuals as positive for the disease.
,Sensitivity is the proportion of truly diseased people in the screened population who are identified as
diseased by the screening test. It is a measure of the probability of correctly diagnosing a case or the
probability that any given case will be identified by the test (e.g., true positives). Specificity is the
proportion of truly non-diseased people who are so identified by the screening test. It is a measure of
the probability of correctly identifying a nondiseased person with the screening test (e.g., true
negatives).
The Central Limit Theorem states that:
A) The sample mean is unbiased
B) The sample mean is approximately normal
C) The parent population of the sample distribution is normally distributed
D) The sample SD is approximately normal
E) Both statements A) and C) can be deduced from the Central Limit Theorem - correct answer ✔✔B)
The sample mean is approximately normal
The Central Limit Theorem states that if the sample size is large enough, the distribution of the
sample means can be approximated by a normal distribution, even if the original population is not
normally distributed. In other words, the distribution of the sample means approaches a normal
distribution as the sample size increases
Assume that a researcher has measured weight in a sample of 100 overweight adults before and after a
diet and exercise program conducted at the local health department's weekly Eat Health - Be Fit
community program.
To determine whether the mean weight decreased six weeks after the exercise program compared to the
initial baseline measures, the researcher should:
A) Compute the correlation coefficient, r, and determine the association between being overweight and
the community program
B) Conduct a t-test for independent samples
C) Conduct a t-test for dependent samples
, D) Conduct a chi-square test for association
E) Not estimate the decrease because there was no control group for the program - correct answer
✔✔C) Conduct a t-test for dependent samples
A t-test is a hypothesis test to compare population means and proportions. In this case, the sample is
dependent because the tests are performed on the same individuals in the sample.
Which of the following estimates of an odds ratio most strongly suggests a computational error?
1) 7.8
2) 1.2
3) -0.9
4) 20.9 - correct answer ✔✔3) -0.9
An odds ratio of -0.9 most strongly indicates a computational error because an odds ratio is calculated
using probabilities, which cannot be negative.
An odds ratio is the probability that an event will occur divided by the probability that it will not occur.
Since probabilities cannot be negative, a negative odds ratio would indicate computational error.
Which measure of mortality would you calculate to determine the proportion of all deaths that is caused
by heart disease?
A) Case Fatality Ratio
B) Randomized Clinical Trial
C) Crude Mortality Rate
D) Proportional Mortality Ratio - correct answer ✔✔D) Proportional Mortality Ratio
the proportion of deaths in a particular population over a specified period of time attributable to a
specific disease
