CERTIFIED IN PUBLIC HEALTH (CPH)
EXAM PREP STUDY GUIDE 2026
COMPLETE QUESTIONS WITH
CORRECT DETAILED ANSWERS || 100%
GUARANTEED PASS <RECENT
VERSION>
Domain 1: Biostatistics
1. Which measure of central tendency is most affected by outliers?
A. Mode
B. Median
C. Mean
D. Interquartile Range
Answer: C. The mean is calculated using all data points, so extreme values can
significantly skew it. The median and mode are more resistant to outliers.
2. A p-value of 0.03 in a hypothesis test suggests:
A. There is a 3% probability the null hypothesis is true.
B. The alternative hypothesis is true.
C. There is a 3% probability of obtaining the observed results (or more extreme) if
the null hypothesis is true.
D. The effect size is large.
Answer: C. This is the correct interpretation of a p-value. It is not the probability
that the null hypothesis is true.
3. Which statistical test is used to compare the means of three or more
independent groups?
A. t-test
B. Chi-square test
C. ANOVA
D. Pearson's correlation
,Answer: C. Analysis of Variance (ANOVA) is used for comparing means across
three or more groups. A t-test is for two groups.
4. A study finds a correlation coefficient (r) of -0.85 between hours of exercise
per week and body fat percentage. This indicates:
A. A weak negative relationship.
B. No relationship.
C. A strong positive relationship.
D. A strong negative relationship.
Answer: D. The sign (-) indicates a negative relationship (as one increases, the
other decreases). The magnitude (0.85) close to 1.0 indicates a strong relationship.
5. Confidence intervals are preferred over p-values because they:
A. Are easier to calculate.
B. Provide a range of plausible values for the population parameter and indicate
precision.
C. Always contain the true population mean.
D. Prove the research hypothesis.
Answer: B. Confidence intervals provide more information than a binary
"significant/non-significant" p-value, as they estimate the effect size and the
uncertainty around it.
6. In a normal distribution, what percentage of data lies within one standard
deviation of the mean?
A. 50%
B. 68%
C. 95%
D. 99.7%
Answer: B. This is a fundamental property of the normal distribution (68-95-99.7
rule).
7. The purpose of a "double-blind" randomized controlled trial is to:
A. Increase the sample size.
B. Prevent both the participants and the researchers from knowing who is in the
treatment or control group.
C. Ensure everyone receives the treatment.
, D. Reduce the cost of the study.
Answer: B. Blinding reduces bias in the assessment of outcomes.
8. A Type I error occurs when:
A. The null hypothesis is accepted when it is false.
B. The null hypothesis is rejected when it is true.
C. The study is underpowered.
D. A one-tailed test is used instead of a two-tailed test.
Answer: B. Type I error is a "false positive."
9. Sensitivity of a diagnostic test is defined as the probability that the test:
A. Is positive when the patient does not have the disease.
B. Is negative when the patient does not have the disease.
C. Is positive when the patient has the disease.
D. Is negative when the patient has the disease.
Answer: C. Sensitivity = True Positives / (True Positives + False Negatives). It
measures the ability to correctly identify those with the disease.
10. The statistical power of a study is the probability of:
A. Making a Type I error.
B. Making a Type II error.
C. Correctly rejecting a false null hypothesis.
D. Correctly accepting a true null hypothesis.
Answer: C. Power is 1 - β (where β is the probability of a Type II error).
Domain 2: Epidemiology
11. The number of new cases of a disease in a population over a specified
period is the:
A. Prevalence
B. Incidence
C. Mortality Rate
D. Attack Rate
Answer: B. Incidence measures new events (cases), while prevalence measures all
existing cases at a point in time.
EXAM PREP STUDY GUIDE 2026
COMPLETE QUESTIONS WITH
CORRECT DETAILED ANSWERS || 100%
GUARANTEED PASS <RECENT
VERSION>
Domain 1: Biostatistics
1. Which measure of central tendency is most affected by outliers?
A. Mode
B. Median
C. Mean
D. Interquartile Range
Answer: C. The mean is calculated using all data points, so extreme values can
significantly skew it. The median and mode are more resistant to outliers.
2. A p-value of 0.03 in a hypothesis test suggests:
A. There is a 3% probability the null hypothesis is true.
B. The alternative hypothesis is true.
C. There is a 3% probability of obtaining the observed results (or more extreme) if
the null hypothesis is true.
D. The effect size is large.
Answer: C. This is the correct interpretation of a p-value. It is not the probability
that the null hypothesis is true.
3. Which statistical test is used to compare the means of three or more
independent groups?
A. t-test
B. Chi-square test
C. ANOVA
D. Pearson's correlation
,Answer: C. Analysis of Variance (ANOVA) is used for comparing means across
three or more groups. A t-test is for two groups.
4. A study finds a correlation coefficient (r) of -0.85 between hours of exercise
per week and body fat percentage. This indicates:
A. A weak negative relationship.
B. No relationship.
C. A strong positive relationship.
D. A strong negative relationship.
Answer: D. The sign (-) indicates a negative relationship (as one increases, the
other decreases). The magnitude (0.85) close to 1.0 indicates a strong relationship.
5. Confidence intervals are preferred over p-values because they:
A. Are easier to calculate.
B. Provide a range of plausible values for the population parameter and indicate
precision.
C. Always contain the true population mean.
D. Prove the research hypothesis.
Answer: B. Confidence intervals provide more information than a binary
"significant/non-significant" p-value, as they estimate the effect size and the
uncertainty around it.
6. In a normal distribution, what percentage of data lies within one standard
deviation of the mean?
A. 50%
B. 68%
C. 95%
D. 99.7%
Answer: B. This is a fundamental property of the normal distribution (68-95-99.7
rule).
7. The purpose of a "double-blind" randomized controlled trial is to:
A. Increase the sample size.
B. Prevent both the participants and the researchers from knowing who is in the
treatment or control group.
C. Ensure everyone receives the treatment.
, D. Reduce the cost of the study.
Answer: B. Blinding reduces bias in the assessment of outcomes.
8. A Type I error occurs when:
A. The null hypothesis is accepted when it is false.
B. The null hypothesis is rejected when it is true.
C. The study is underpowered.
D. A one-tailed test is used instead of a two-tailed test.
Answer: B. Type I error is a "false positive."
9. Sensitivity of a diagnostic test is defined as the probability that the test:
A. Is positive when the patient does not have the disease.
B. Is negative when the patient does not have the disease.
C. Is positive when the patient has the disease.
D. Is negative when the patient has the disease.
Answer: C. Sensitivity = True Positives / (True Positives + False Negatives). It
measures the ability to correctly identify those with the disease.
10. The statistical power of a study is the probability of:
A. Making a Type I error.
B. Making a Type II error.
C. Correctly rejecting a false null hypothesis.
D. Correctly accepting a true null hypothesis.
Answer: C. Power is 1 - β (where β is the probability of a Type II error).
Domain 2: Epidemiology
11. The number of new cases of a disease in a population over a specified
period is the:
A. Prevalence
B. Incidence
C. Mortality Rate
D. Attack Rate
Answer: B. Incidence measures new events (cases), while prevalence measures all
existing cases at a point in time.
