CPH - ALL SAMPLE EXAM QUESTIONS AND ANSWERS
2026 VERIFIED 2026
Overview
This comprehensive document provides a complete collection of sample questions and
verified answers for the Certified in Public Health (CPH) exam, updated for the 2026
testing cycle. It covers all core public health domains including epidemiology,
biostatistics, environmental health, health policy and management, social and behavioral
sciences, leadership, ethics, and program evaluation. All answers are accurate and
aligned with current CPH certification standards for 2026, making this an essential
resource for exam preparation and self-assessment.
Question 1
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
Rationale: The data contain an extreme outlier (16 days) that skews the distribution and
inflates the mean. The median (1.5 days) is resistant to outliers and better represents the
central tendency. The range (0-16 days) provides a simple measure of spread that is also
not distorted by the skewed distribution. The mean and standard deviation would be
heavily influenced by the outlier .
Question 2
An epidemiologist attempts to predict the weight of an elderly person from demispan.
She randomly chooses 70 elderly subjects and records their weight and demispan
measurements. Given that the value of the Pearson correlation coefficient is zero, what
can be deduced?
,A) 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
Rationale: A Pearson correlation coefficient of zero indicates the absence of a linear
relationship between the two variables. However, a nonlinear relationship (e.g., U-shaped
or exponential) could still exist and would not be captured by the Pearson correlation. The
correlation coefficient measures only the strength and direction of a linear association .
Question 3
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
Rationale: Tukey's test is a parametric post-hoc test used after ANOVA to compare
multiple group means. The Kruskal-Wallis, Wilcoxon rank-sum, and Mann-Whitney tests
are all nonparametric tests that do not assume normal distribution of the data.
Nonparametric tests are used when parametric assumptions are violated .
Question 4
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
Rationale: A scale of 0 to 5 with ordered categories represents an ordinal variable because
the values have a meaningful rank order, but the intervals between values may not be
,equal. Ordinal data are commonly used in Likert-scale questions and patient-reported
outcomes. Ratio variables have a true zero, interval variables have equal intervals, and
nominal variables have no inherent order .
Question 5
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
Rationale: The least squares method minimizes the sum of squared vertical distances
(residuals) between observed data points and the regression line. This produces the best-
fitting line that minimizes prediction error. R-square measures the proportion of variance
explained, and regression is the overall modeling approach, not the specific method for
estimating coefficients .
Question 6
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
Rationale: Sensitivity is the proportion of truly diseased individuals who are correctly
identified as positive by the screening test (true positives). Therefore, with 95% sensitivity,
, 95 out of 100 diseased individuals will test positive. Specificity (90%) refers to correctly
identifying non-diseased individuals as negative. The positive predictive value depends on
disease prevalence and is not provided in this scenario .
Question 7
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
Rationale: The Central Limit Theorem states that the distribution of sample means
approaches a normal distribution as the sample size increases, regardless of the shape of
the original population distribution. This fundamental theorem enables hypothesis testing
and confidence interval construction using normal approximations even when the
underlying population is not normally distributed .
Question 8
Assume that a researcher has measured weight in a sample of 100 overweight adults
before and after a diet and exercise 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
Rationale: A paired (dependent) t-test is appropriate because the same individuals are
measured before and after the intervention. This design uses each participant as their own
2026 VERIFIED 2026
Overview
This comprehensive document provides a complete collection of sample questions and
verified answers for the Certified in Public Health (CPH) exam, updated for the 2026
testing cycle. It covers all core public health domains including epidemiology,
biostatistics, environmental health, health policy and management, social and behavioral
sciences, leadership, ethics, and program evaluation. All answers are accurate and
aligned with current CPH certification standards for 2026, making this an essential
resource for exam preparation and self-assessment.
Question 1
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
Rationale: The data contain an extreme outlier (16 days) that skews the distribution and
inflates the mean. The median (1.5 days) is resistant to outliers and better represents the
central tendency. The range (0-16 days) provides a simple measure of spread that is also
not distorted by the skewed distribution. The mean and standard deviation would be
heavily influenced by the outlier .
Question 2
An epidemiologist attempts to predict the weight of an elderly person from demispan.
She randomly chooses 70 elderly subjects and records their weight and demispan
measurements. Given that the value of the Pearson correlation coefficient is zero, what
can be deduced?
,A) 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
Rationale: A Pearson correlation coefficient of zero indicates the absence of a linear
relationship between the two variables. However, a nonlinear relationship (e.g., U-shaped
or exponential) could still exist and would not be captured by the Pearson correlation. The
correlation coefficient measures only the strength and direction of a linear association .
Question 3
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
Rationale: Tukey's test is a parametric post-hoc test used after ANOVA to compare
multiple group means. The Kruskal-Wallis, Wilcoxon rank-sum, and Mann-Whitney tests
are all nonparametric tests that do not assume normal distribution of the data.
Nonparametric tests are used when parametric assumptions are violated .
Question 4
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
Rationale: A scale of 0 to 5 with ordered categories represents an ordinal variable because
the values have a meaningful rank order, but the intervals between values may not be
,equal. Ordinal data are commonly used in Likert-scale questions and patient-reported
outcomes. Ratio variables have a true zero, interval variables have equal intervals, and
nominal variables have no inherent order .
Question 5
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
Rationale: The least squares method minimizes the sum of squared vertical distances
(residuals) between observed data points and the regression line. This produces the best-
fitting line that minimizes prediction error. R-square measures the proportion of variance
explained, and regression is the overall modeling approach, not the specific method for
estimating coefficients .
Question 6
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
Rationale: Sensitivity is the proportion of truly diseased individuals who are correctly
identified as positive by the screening test (true positives). Therefore, with 95% sensitivity,
, 95 out of 100 diseased individuals will test positive. Specificity (90%) refers to correctly
identifying non-diseased individuals as negative. The positive predictive value depends on
disease prevalence and is not provided in this scenario .
Question 7
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
Rationale: The Central Limit Theorem states that the distribution of sample means
approaches a normal distribution as the sample size increases, regardless of the shape of
the original population distribution. This fundamental theorem enables hypothesis testing
and confidence interval construction using normal approximations even when the
underlying population is not normally distributed .
Question 8
Assume that a researcher has measured weight in a sample of 100 overweight adults
before and after a diet and exercise 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
Rationale: A paired (dependent) t-test is appropriate because the same individuals are
measured before and after the intervention. This design uses each participant as their own
