Principles of Epidemiology & Biostatistics: Final Exam Review, Exams of Nursing

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HLTH 4 85

Principles of Epidemiology &

Biostatistics

LATEST FINAL EXAM REVIEW

Q & S

1. An epidemiological study is conducted to assess the relationship between physical activity and heart disease in a population. What type of study is most appropriate for assessing this association?
   • A. Cross-sectional study
   • B. Cohort study
   • C. Case-control study
   • D. Clinical trial Correct Answer : B. Cohort study
   • Rationale: A cohort study is suitable for assessing the relationship between risk factors (e.g., physical activity) and outcomes (e.g., heart disease) over time.
2. Which statistical test is most appropriate for comparing the means of more than two independent groups?
   • A. Chi-square test
   • B. t-test
   • C. ANOVA
   • D. Mann-Whitney U test Correct Answer : C. ANOVA

• Rationale: ANOVA (Analysis of Variance) is used to compare the means of three or more independent groups.

3. Which of the following is a measure of disease frequency that refers to the number of new cases of a disease in a population over a specified period?

• A. Prevalence
• B. Incidence rate
• C. Mortality rate
• D. Case fatality rate Correct Answer : B. Incidence rate
• Rationale: Incidence rate measures the occurrence of new cases in a specified time period.

4. In biostatistics, the p-value is used to:

• A. Measure the strength of relationship
• B. Identify the population parameter
• C. Determine the sample size
• D. Assess the strength of evidence against the null hypothesis

Correct Answer : D. Assess the strength of evidence against the null hypothesis

• Rationale: The p-value helps in determining how compatible the data are with the null hypothesis.

5. What is the primary goal of a randomized controlled trial (RCT) in epidemiological studies?

• A. To establish a temporal relationship
• B. To eliminate selection bias
• C. To establish causation
• D. To measure prevalence Correct Answer : C. To establish causation
• Rationale: Randomized controlled trials are designed to determine the cause-effect relationship by controlling for confounding factors. Fill-in-the-Blank Questions:

6. The ________ effect is a phenomenon where trial participants improve simply because they are being observed in a study. Correct Answer : Hawthorne

• Rationale: The Hawthorne effect refers to participants altering their behavior because they are aware of being observed.

7. In survival analysis, the time it takes for an event (such as death or relapse) to occur is typically analyzed using ________ methods. Correct Answer : Kaplan-Meier

• Rationale: Kaplan-Meier methods are used to estimate survival functions and examine survival data.

8. The ________ is the range within which we expect the true population parameter to lie, given a certain level of confidence. Correct Answer : Confidence interval

• Rationale: Confidence intervals provide a range of values that is likely to contain the population parameter.

9. A Type I error occurs when the null hypothesis is ________. Correct Answer : rejected when it is true

• Rationale: A Type I error involves rejecting a true null hypothesis, often referred to as a "false positive."

10. The ________ bias occurs when participants are incorrectly categorized into exposure groups. Correct Answer : Misclassification

• Rationale: Misclassification bias arises when there are errors in the classification of exposure or disease status. True/False Questions:

11. Epidemiology primarily focuses on the individual level, rather than populations. Correct Answer : False

• Rationale: Epidemiology focuses on the distribution and determinants of health-related states in populations.

12. In statistical terms, power is the probability of correctly rejecting the null hypothesis when it is false. Correct Answer : True

• Rationale: Statistical power measures a test's ability to detect an effect if there is one.

13. Confounding can be completely eliminated by matching in a case-control study. Correct Answer : False

• Rationale: Matching can control for confounding factors but cannot eliminate them completely.

14. Interaction effects in epidemiology indicate that the effect of one exposure depends on the level of another variable. Correct Answer : True

• Rationale: Interaction effects occur when the effect of one variable is modified by the presence of another.

15. A higher standard deviation in a dataset indicates more variability from the mean. Correct Answer : True

• Rationale: Standard deviation quantifies the amount of variation or dispersion in a set of values. Multiple Response Questions:

16. Which of the following are measures of central tendency? (Choose all that apply)
    • A. Mean
    • B. Mode
    • C. Median
    • D. Range Correct Answer s: A. Mean, B. Mode, C. Median
    • Rationale: Mean, median, and mode are all measures of central tendency, while range is a measure of dispersion.
17. Which factors can lead to bias in epidemiological studies? (Choose all that apply)
    • A. Selection bias
    • B. Information bias
    • C. Random error
    • D. Confounding Correct Answer s: A. Selection bias, B. Information bias, D. Confounding
    • Rationale: Selection bias, information bias, and confounding are common sources of bias, while random error is a type of error rather than bias.

18. Which of the following statements are true regarding cluster sampling? (Choose all that apply)
    • A. It's used when a complete list of all members is not feasible.
    • B. It reduces variability within clusters.
    • C. It improves within-cluster reliability.
    • D. It may increase sampling error compared to simple random sampling. Correct Answer s: A. It's used when a complete list of all members is not feasible, D. It may increase sampling error compared to simple random sampling.
    • Rationale: Cluster sampling is used for practical reasons when a full list isn't available, but it typically increases sampling error due to similarity within clusters.
19. In a case-control study, which strategies can be used to address confounding? (Choose all that apply)
    • A. Randomization
    • B. Matching
    • C. Stratification
    • D. Multivariable analysis

Correct Answer s: B. Matching, C. Stratification, D. Multivariable analysis

• Rationale: Randomization is not feasible in case-control studies, but matching, stratification, and multivariable analysis can address confounding.

20. Which statistical procedures can be used to evaluate the hypothesis of no interaction between two variables? (Choose all that apply)

• A. Stratified analysis
• B. Logistic regression
• C. Linear regression
• D. Chi-square test for trend Correct Answer s: A. Stratified analysis, B. Logistic regression, C. Linear regression
• Rationale: These methods allow for assessment of interactions between variables. Additional Questions:

21. What test is most appropriate for comparing the distribution of a categorical variable across two independent groups?

• A. Chi-square test

• B. Paired t-test
• C. Wilcoxon signed-rank test
• D. Spearman's rank correlation Correct Answer : A. Chi-square test
• Rationale: The Chi-square test is used for assessing relationships between categorical variables.

22. Which epidemiological study design is best suited for rare diseases?

• A. Case-control study
• B. Cohort study
• C. Cross-sectional study
• D. Randomized controlled trial Correct Answer : A. Case-control study
• Rationale: Case-control studies are efficient for studying rare diseases by focusing on cases and a control group for comparison.

23. Fill in the blank: The ability of a test to correctly identify those with the disease is known as ________.

Correct Answer : Sensitivity

• Rationale: Sensitivity measures the test's ability to identify true positives.

24. True or False: All biases can be controlled by increasing the sample size. Correct Answer : False

• Rationale: Increasing sample size reduces random error, not systematic biases.

25. Which of the following are considered non-parametric tests? (Choose all that apply)

• A. Mann-Whitney U test
• B. Kruskal-Wallis test
• C. Paired t-test
• D. Friedman test Correct Answer s: A. Mann-Whitney U test, B. Kruskal- Wallis test, D. Friedman test
• Rationale: Non-parametric tests do not assume a specific distribution and are used for ordinal data or non-normally distributed interval data.

26. Multiple choice: A public health department wants to evaluate the effect of a new anti-smoking campaign. Which metric should they use to measure its effectiveness?
    • A. Prevalence of smokers before and after the campaign
    • B. Incidence of smoking-related diseases
    • C. Mortality rate from all causes
    • D. Birth rate Correct Answer : A. Prevalence of smokers before and after the campaign
    • Rationale: Prevalence measures the campaign’s effectiveness by comparing smoking rates before and after.
27. Fill in the blank: ________ sampling involves dividing the population into subgroups and then taking a random sample from each subgroup. Correct Answer : Stratified
    • Rationale: Stratified sampling ensures representation from each subgroup by sampling separately within strata.

28. Multiple Response: For findings from an observational study to be generalizable, which of the following factors are important? (Choose all that apply)
    • A. Randomization
    • B. Representative sample
    • C. External validity
    • D. Blinding Correct Answer s: B. Representative sample, C. External validity
    • Rationale: A representative sample and good external validity ensure that the findings can be applied to other populations.
29. True or False: Odds ratios can approximate relative risk if the outcome is rare. Correct Answer : True
    • Rationale: When outcomes are rare, odds ratios closely approximate relative risks.
30. Which of the following can decrease the width of a confidence interval? (Choose all that apply)

• A. Increasing sample size
• B. Decreasing variability in data
• C. Increasing the confidence level
• D. Reducing the effect size Correct Answer s: A. Increasing sample size, B. Decreasing variability in data
• Rationale: Larger sample sizes and lower variability reduce the margin of error, thus narrowing the confidence interval.

1. Multiple Choice: A pharmaceutical company is conducting a clinical trial for a new drug to treat hypertension. The trial involves 1000 participants, randomly assigned to either the treatment group or the control group. The company is interested in determining the effectiveness of the drug in lowering blood pressure. What type of study design is being used in this scenario? (a) Case-control study (b) Cohort study (c) Cross-sectional study (d) Randomized controlled trial Correct Answer : (d) Randomized controlled trial

Rationale: A randomized controlled trial (RCT) is the gold standard for evaluating the effectiveness of interventions. In an RCT, participants are randomly assigned to treatment or control groups, allowing for the control of confounding variables and minimizing bias.

2. Fill-in-the-Blank: The __ is a measure of the strength of association between an exposure and an outcome, expressed as the ratio of the odds of the outcome in the exposed group to the odds of the outcome in the unexposed group. Correct Answer : Odds Ratio Rationale: The odds ratio (OR) is a commonly used measure in case-control studies to quantify the association between an exposure and an outcome.
3. True/False: A p-value of 0.05 indicates that there is a 5% chance of observing the results of the study if the null hypothesis is true. Correct Answer : True Rationale: The p-value represents the probability of obtaining the observed results or more extreme results if the null hypothesis is

true. A p-value of 0.05 indicates that there is a 5% chance of observing the results of the study if the null hypothesis is true.

4. Multiple Response: Which of the following are potential sources of bias in a study? (a) Selection bias (b) Information bias (c) Confounding bias (d) Randomization bias Correct Answer : (a), (b), (c) Rationale: Selection bias, information bias, and confounding bias are all potential sources of bias in a study. Randomization bias is not a recognized type of bias.
5. Multiple Choice: A researcher is interested in studying the association between smoking and lung cancer. The researcher collects data on the smoking habits and lung cancer status of 1000 individuals. What type of study design is being used in this scenario?

(a) Case-control study (b) Cohort study (c) Cross-sectional study (d) Randomized controlled trial Correct Answer : (c) Cross-sectional study Rationale: A cross-sectional study collects data on exposure and outcome at a single point in time. In this scenario, the researcher is collecting data on smoking habits and lung cancer status simultaneously, making it a cross-sectional study.

6. Fill-in-the-Blank: The __ is a measure of the variability of a sample, calculated as the square root of the variance. Correct Answer : Standard Deviation Rationale: The standard deviation is a measure of the spread of data around the mean. It is calculated as the square root of the variance.
7. True/False: A confidence interval provides a range of values that is likely to contain the true population parameter.

Correct Answer : True Rationale: A confidence interval provides a range of values that is likely to contain the true population parameter. The width of the confidence interval reflects the precision of the estimate.

8. Multiple Response: Which of the following are statistical tests used to compare means? (a) t-test (b) ANOVA (c) Chi-square test (d) Wilcoxon rank-sum test Correct Answer : (a), (b), (d) Rationale: The t-test, ANOVA, and Wilcoxon rank-sum test are all statistical tests used to compare means. The chi-square test is used to compare proportions.
9. Multiple Choice: A company is interested in determining the effectiveness of a new marketing campaign in increasing sales. The

company collects data on sales before and after the campaign launch. What type of study design is being used in this scenario? (a) Case-control study (b) Cohort study (c) Cross-sectional study (d) Before-and-after study Correct Answer : (d) Before-and-after study Rationale: A before-and-after study compares outcomes before and after an intervention. In this scenario, the company is comparing sales before and after the marketing campaign launch, making it a before-and-after study.

10. Fill-in-the-Blank: The __ is a measure of the strength of association between an exposure and an outcome, expressed as the ratio of the incidence rate in the exposed group to the incidence rate in the unexposed group. Correct Answer : Relative Risk

Rationale: The relative risk (RR) is a commonly used measure in cohort studies to quantify the association between an exposure and an outcome.

11. True/False: A type I error occurs when the null hypothesis is rejected when it is actually true. Correct Answer : True Rationale: A type I error, also known as a false positive, occurs when the null hypothesis is rejected when it is actually true.
12. Multiple Response: Which of the following are measures of central tendency? (a) Mean (b) Median (c) Mode (d) Standard deviation Correct Answer : (a), (b), (c)

Rationale: The mean, median, and mode are all measures of central tendency. The standard deviation is a measure of variability.

13. Multiple Choice: A researcher is interested in studying the relationship between age and the incidence of heart disease. The researcher collects data on the age and heart disease status of 1000 individuals. What type of study design is being used in this scenario? (a) Case-control study (b) Cohort study (c) Cross-sectional study (d) Randomized controlled trial Correct Answer : (c) Cross-sectional study Rationale: A cross-sectional study collects data on exposure and outcome at a single point in time. In this scenario, the researcher is collecting data on age and heart disease status simultaneously, making it a cross-sectional study.
14. Fill-in-the-Blank: The __ is a statistical test used to compare proportions between two or more groups.

Correct Answer : Chi-square test Rationale: The chi-square test is a statistical test used to compare proportions between two or more groups.

15. True/False: A type II error occurs when the null hypothesis is not rejected when it is actually false. Correct Answer : True Rationale: A type II error, also known as a false negative, occurs when the null hypothesis is not rejected when it is actually false.
16. Multiple Response: Which of the following are types of observational studies? (a) Case-control study (b) Cohort study (c) Cross-sectional study (d) Randomized controlled trial Correct Answer : (a), (b), (c)

Rationale: Case-control studies, cohort studies, and cross-sectional studies are all types of observational studies. Randomized controlled trials are experimental studies.

17. Multiple Choice: A company is interested in determining the impact of a new product launch on customer satisfaction. The company collects data on customer satisfaction ratings before and after the product launch. What type of study design is being used in this scenario? (a) Case-control study (b) Cohort study (c) Cross-sectional study (d) Before-and-after study Correct Answer : (d) Before-and-after study Rationale: A before-and-after study compares outcomes before and after an intervention. In this scenario, the company is comparing customer satisfaction ratings before and after the product launch, making it a before-and-after study.

18. Fill-in-the-Blank: The __ is a measure of the strength of association between an exposure and an outcome, expressed as the ratio of the incidence rate in the exposed group to the incidence rate in the unexposed group. Correct Answer : Relative Risk Rationale: The relative risk (RR) is a commonly used measure in cohort studies to quantify the association between an exposure and an outcome.
19. True/False: A p-value of 0.01 indicates that there is a 1% chance of observing the results of the study if the null hypothesis is true. Correct Answer : True Rationale: The p-value represents the probability of obtaining the observed results or more extreme results if the null hypothesis is true. A p-value of 0.01 indicates that there is a 1% chance of observing the results of the study if the null hypothesis is true.
20. Multiple Response: Which of the following are factors that can influence the power of a study?