# 100 multiple-choice questions (MCQs) for biostatistics

By | July 31, 2023

1. What is the primary objective of biostatistics?
a) To analyze data from clinical trials
b) To study biological processes
c) To apply statistical methods to biological data
d) To develop new medical treatments

2. Which of the following is an example of quantitative data?
a) Blood type
b) Gender
c) Age
d) Eye color

3. Which statistical measure is used to describe the spread or dispersion of data points around the mean?
a) Median
b) Mode
c) Variance
d) Skewness

4. What is the purpose of a control group in a randomized controlled trial (RCT)?
a) To provide a comparison to the experimental group
b) To ensure all participants are treated equally
c) To maximize the sample size
d) To reduce the risk of bias

5. Which type of study design is commonly used to study the causes of diseases?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Experimental study

6. What is the p-value in hypothesis testing?
a) The probability of making a Type I error
b) The probability of making a Type II error
c) The level of significance
d) The probability of obtaining the observed results by chance alone

7. Which statistical test is used to compare means between two groups?
a) Chi-square test
b) T-test
c) ANOVA
d) Wilcoxon rank-sum test

8. In a normal distribution, what percentage of data falls within one standard deviation of the mean?
a) 34.13%
b) 50%
c) 68.27%
d) 95.45%

9. What does the term “odds ratio” represent in epidemiological studies?
a) The difference between two groups’ odds of an event occurring
b) The relative risk of an event occurring in one group compared to another
c) The absolute risk of an event occurring in one group
d) The number needed to treat (NNT) to prevent one event

10. What is the purpose of blinding in a clinical trial?
a) To keep the researchers unbiased
b) To keep the participants unaware of the treatment they receive
c) To prevent confounding variables from affecting the results
d) To ensure the sample size is large enough

11. Which of the following measures of central tendency is affected most by extreme outliers?
a) Mean
b) Median
c) Mode
d) Standard deviation

12. A researcher is investigating the association between smoking and lung cancer. What type of study design would be most appropriate?
a) Randomized controlled trial
b) Case-control study
c) Cohort study
d) Cross-sectional study

13. Which type of bias occurs when participants who do not complete a study differ from those who do?
a) Selection bias
b) Information bias
c) Confounding bias
d) Attrition bias

14. Which statistical test is used to analyze the association between two categorical variables?
a) T-test
b) Chi-square test
c) ANOVA
d) Pearson correlation coefficient

15. Which of the following is an example of a continuous variable?
a) Gender
b) Marital status
c) Height
d) Blood type

16. What does the term “p < 0.05” indicate in hypothesis testing?
a) The results are statistically significant
b) The results are not statistically significant
c) The effect size is large
d) The sample size is small

17. In which phase of a clinical trial are potential side effects and safety assessed?
a) Phase I
b) Phase II
c) Phase III
d) Phase IV

18. Which measure of dispersion is not affected by extreme values in a dataset?
a) Range
b) Variance
c) Interquartile range (IQR)
d) Standard deviation

19. What does the term “confidence interval” represent in statistics?
a) The range of values within which the true population parameter is likely to lie
b) The margin of error in a statistical estimate
c) The probability of rejecting the null hypothesis
d) The level of significance

20. Which type of study design is most susceptible to recall bias?
a) Randomized controlled trial
b) Case-control study
c) Cohort study
d) Cross-sectional study

21. Which statistical test is used to compare means between multiple groups?
a) T-test
b) Chi-square test
c) ANOVA
d) Wilcoxon rank-sum test

22. A researcher is investigating the relationship between age and blood pressure. Which type of correlation is the most appropriate?
a) Positive correlation
b) Negative correlation
c) No correlation
d) Partial correlation

23. Which statistical test is used to analyze the association between two continuous variables?
a) T-test
b) Chi-square test
c) Correlation coefficient
d) ANOVA

24. What does the term “sensitivity” represent in diagnostic testing?
a) The probability of a positive test result in individuals without the disease
b) The probability of a positive test result in individuals with the disease
c) The ability of the test to correctly identify individuals with the disease
d) The ability of the test to correctly identify individuals without the disease

25. In a clinical trial, what is the purpose of randomization?
a) To ensure all participants receive the same treatment
b) To ensure the study is double-blinded
c) To minimize bias and confounding variables
d) To increase the likelihood of a statistically significant result

26. What is the difference between a parameter and a statistic in statistics?
a) A parameter is a characteristic of a sample, while a statistic is a characteristic of a population.
b) A parameter is a characteristic of a population, while a statistic is a characteristic of a sample.
c) A parameter is used in descriptive statistics, while a statistic is used in inferential statistics.
d) A parameter is used in inferential statistics, while a statistic is used in descriptive statistics.

27. Which type of bias occurs when participants misreport their exposure or outcome status?
a) Selection bias
b) Information bias
c) Confounding bias
d) Recall bias

28. What is the purpose of stratified sampling in research studies?
a) To increase the sample size
b) To reduce the risk of selection bias
c) To increase the external validity of the study
d) To ensure equal representation of all demographic groups

29. Which of the following is a measure of relative risk in epidemiological studies?
a) Odds ratio
b) Standard deviation
c) Hazard ratio
d) Variance

30. In a normal distribution, what percentage of data falls within two standard deviations of the mean?
a) 34.13%
b) 50%
c) 68.27%
d) 95.45%

31. Which statistical test is used to compare proportions between two groups?
a) T-test
b) Chi-square test
c) ANOVA
d) Wilcoxon rank-sum test

32. What is the purpose of a placebo in a clinical trial?
a) To provide a reference point for comparison
b) To ensure participants

are blinded to the treatment
c) To ensure the study is double-blinded
d) To maximize the placebo effect

33. Which type of study design is best suited for establishing cause-and-effect relationships?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Experimental study

34. Which statistical measure is used to summarize the variability of a sample mean estimate?
a) Median
b) Mode
c) Variance
d) Standard error

35. What does the term “type I error” refer to in hypothesis testing?
a) Incorrectly rejecting a true null hypothesis
b) Incorrectly accepting a false null hypothesis
c) Incorrectly rejecting a false null hypothesis
d) Incorrectly accepting a true null hypothesis

36. What is the purpose of a two-sample t-test?
a) To compare the means of two independent groups
b) To compare the means of two paired groups
c) To compare the variances of two independent groups
d) To compare the proportions of two independent groups

37. In a contingency table, what does the term “marginal totals” represent?
a) The total number of observations in each row and column
b) The sum of the cell frequencies
c) The average value of the cells in each row and column
d) The standard deviation of the cell frequencies

38. Which measure of central tendency is most appropriate for ordinal data?
a) Mean
b) Median
c) Mode
d) Standard deviation

39. Which of the following statements about the normal distribution is true?
a) It is positively skewed.
b) The mean, median, and mode are equal.
c) The area under the curve is always less than 1.
d) It is a discrete probability distribution.

40. What does the term “power” refer to in statistical hypothesis testing?
a) The probability of correctly rejecting a false null hypothesis
b) The probability of correctly accepting a true null hypothesis
c) The level of significance
d) The probability of making a Type I error

41. Which statistical test is used to compare means between multiple groups and control for confounding variables?
a) T-test
b) Chi-square test
c) ANOVA
d) Regression analysis

42. What is the purpose of the Central Limit Theorem in statistics?
a) To determine the sample size needed for a study
b) To describe the shape of a normal distribution
c) To estimate population parameters from sample statistics
d) To calculate the variance of a sample

43. Which type of bias occurs when the study results are influenced by factors other than the exposure or intervention being studied?
a) Selection bias
b) Information bias
c) Confounding bias
d) Observer bias

44. What is the purpose of a Kaplan-Meier survival curve?
a) To compare the survival rates of different groups over time
b) To assess the normality of a distribution
c) To estimate the population mean
d) To visualize the spread of data points

45. In a chi-square test, what does the chi-square statistic represent?
a) The difference between the observed and expected frequencies
b) The measure of effect size
c) The probability of a Type I error
d) The probability of a Type II error

46. Which statistical test is used to analyze the association between a categorical variable and a continuous variable?
a) T-test
b) Chi-square test
c) ANOVA
d) Regression analysis

47. In a randomized controlled trial, what is the purpose of intention-to-treat (ITT) analysis?
a) To assess the efficacy of the treatment on the per-protocol population
b) To minimize the risk of selection bias
c) To analyze the data without considering the treatment assignment
d) To control for confounding variables

48. Which of the following study designs is most appropriate for investigating rare diseases or outcomes?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Randomized controlled trial

49. What is the purpose of a p-value in hypothesis testing?
a) To determine the effect size of the study
b) To assess the statistical power of the study
c) To measure the probability of obtaining the observed results by chance alone
d) To calculate the margin of error in the study

50. Which statistical measure is used to describe the shape of a distribution?
a) Median
b) Mode
c) Skewness
d) Standard deviation

51. What does the term “confidence level” represent in statistics?
a) The level of significance used in hypothesis testing
b) The probability of making a Type I error
c) The probability of making a Type II error
d) The level of certainty in the interval estimate

52. Which type of bias occurs when participants are not representative of the target population?
a) Selection bias
b) Information bias
c) Confounding bias
d) Sampling bias

53. What is the purpose of a correlation coefficient in statistics?
a) To measure the strength of the relationship between two variables
b) To determine the direction of causation between two variables
c) To calculate the margin of error in a study
d) To assess the normality of a distribution

54. Which type of study design is commonly used to study the prevalence of a disease or condition?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Experimental study

55. 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) Wilcoxon rank-sum test

56. What does the term “p-value” stand for in hypothesis testing?
a) Probability value
b) Population value
c) Percentage value
d) Power value

57. In a normal distribution, what percentage of data falls within three standard deviations of the mean?
a) 34.13%
b) 50%
c) 68.27%
d) 99.73%

58. Which type of bias occurs when the study results are affected by the way data are collected, recorded, or interpreted?
a) Selection bias
b) Information bias
c) Confounding bias
d) Observer bias

59. What is the purpose of a placebo in a randomized controlled trial?
a) To ensure all participants receive the same treatment
b) To provide a reference point for comparison
c) To maximize the placebo effect
d) To minimize bias and confounding variables

60. Which measure of central tendency is most appropriate for nominal data?
a) Mean
b) Median
c) Mode
d) Standard deviation

61. What is the difference between a null hypothesis and an alternative hypothesis in hypothesis testing?
a) A null hypothesis states that there is no effect, while an alternative hypothesis states that there is an effect.
b) A null hypothesis states that there is an effect, while an alternative hypothesis states that there is no effect.
c) A null hypothesis is always rejected, while an alternative hypothesis is always accepted.
d) A null hypothesis is always accepted, while an alternative hypothesis is always rejected.

62. Which type of sampling method involves dividing the population into subgroups and then selecting a random sample from each subgroup?
a) Simple random sampling
b) Stratified sampling
c) Convenience sampling
d) Cluster sampling

63

. What does the term “standard deviation” represent in statistics?
a) The average value of a dataset
b) The spread or dispersion of data points around the mean
c) The difference between the highest and lowest values in a dataset
d) The proportion of data points that fall within one standard deviation of the mean

64. Which type of study design is best suited for studying the prevalence of a disease at a specific point in time?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Experimental study

65. Which statistical test is used to compare means between two paired groups?
a) T-test
b) Chi-square test
c) Paired t-test
d) Wilcoxon signed-rank test

66. What is the purpose of a sample size calculation in research studies?
a) To determine the effect size of the study
b) To assess the normality of the distribution
c) To estimate the population parameters
d) To ensure the study has sufficient statistical power

67. Which type of bias occurs when participants who experience a particular outcome are more or less likely to be included in the study?
a) Selection bias
b) Information bias
c) Confounding bias
d) Survivorship bias

68. Which statistical test is used to analyze the association between three or more categorical variables?
a) T-test
b) Chi-square test
c) ANOVA
d) Regression analysis

69. In a contingency table, what does the term “expected frequencies” represent?
a) The sum of the cell frequencies
b) The frequency of a specific event
c) The frequency distribution of the variables
d) The frequencies that would be expected under the assumption of independence

70. What does the term “alpha level” represent in hypothesis testing?
a) The level of significance used to determine statistical significance
b) The probability of making a Type I error
c) The probability of making a Type II error
d) The measure of effect size

71. Which type of bias occurs when the exposure and outcome are measured at the same time, leading to an incorrect association?
a) Selection bias
b) Information bias
c) Confounding bias
d) Temporal bias

72. What is the purpose of a hazard ratio in survival analysis?
a) To measure the strength of the relationship between two continuous variables
b) To compare the means of two independent groups
c) To assess the normality of a distribution
d) To estimate the relative risk of an event occurring over time

73. Which statistical measure is used to describe the strength and direction of a linear relationship between two continuous variables?
a) Median
b) Mode
c) Correlation coefficient
d) Standard deviation

74. In a chi-square test, what does the null hypothesis state?
a) There is a significant difference between the observed and expected frequencies.
b) There is no significant difference between the observed and expected frequencies.
c) The population proportion is equal to the sample proportion.
d) The population mean is equal to the sample mean.

75. Which type of study design is most appropriate for investigating the incidence of a disease or outcome over time?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Experimental study

76. What does the term “effect size” represent in statistics?
a) The probability of rejecting the null hypothesis
b) The level of significance used in hypothesis testing
c) The strength of the relationship between two variables
d) The difference between the observed and expected frequencies

77. Which statistical test is used to analyze the association between a categorical variable and a continuous variable while controlling for other variables?
a) T-test
b) Chi-square test
c) ANOVA
d) Multiple regression analysis

78. What is the purpose of a scatter plot in data visualization?
a) To display the distribution of a single variable
b) To compare the means of two independent groups
c) To visualize the relationship between two continuous variables
d) To summarize categorical data

79. Which type of bias occurs when the study population is not representative of the target population due to non-random selection?
a) Selection bias
b) Information bias
c) Confounding bias
d) Sampling bias

80. What is the purpose of a 95% confidence interval?
a) To provide a range of values within which the true population parameter is likely to lie
b) To determine the level of significance in hypothesis testing
c) To calculate the margin of error in a study
d) To estimate the standard deviation of a sample

81. Which statistical test is used to analyze the association between two continuous variables while controlling for other variables?
a) T-test
b) Chi-square test
c) ANOVA
d) Multiple regression analysis

82. In a randomized controlled trial, what is the purpose of a washout period?
a) To ensure all participants receive the same treatment
b) To minimize the risk of selection bias
c) To eliminate the effects of prior treatments or interventions
d) To control for confounding variables

83. What does the term “survival analysis” refer to in biostatistics?
a) The analysis of continuous variables over time
b) The analysis of survival rates and times in a study population
c) The analysis of categorical variables and their associations
d) The analysis of the effects of interventions on health outcomes

84. Which type of study design is most appropriate for investigating the natural history of a disease or condition?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Experimental study

85. What is the purpose of a Z-test in hypothesis testing?
a) To compare the means of two independent groups
b) To compare the means of two paired groups
c) To compare the means of three or more independent groups
d) To compare the means of a sample to a known population mean

86. Which statistical test is used to analyze the association between two categorical variables while controlling for other variables?
a) T-test
b) Chi-square test
c) ANOVA
d) Multiple logistic regression analysis

87. What is the purpose of a Kaplan-Meier estimator in survival analysis?
a) To estimate the population mean
b) To calculate the variance of a sample
c) To estimate the survival function over time
d) To assess the normality of a distribution

88. Which type of bias occurs when participants provide responses that they believe the researcher wants to hear?
a) Selection bias
b) Information bias
c) Confounding bias
d) Social desirability bias

89. What is the purpose of a sensitivity analysis in statistical modeling?
a) To determine the effect size of the study
b) To assess the normality of the distribution
c) To estimate the population parameters
d) To evaluate the robustness of the results to different assumptions

90. Which statistical measure is used to describe the relationship between two categorical variables in a contingency table?
a) Median
b) Mode
c) Odds ratio
d) Standard deviation

91. In a chi-square test, what does the degrees of freedom represent?
a) The difference between the observed and expected frequencies
b) The number of cells in a contingency table
c) The number of categories in a variable
d) The number of independent variables in the analysis

92. Which type of

bias occurs when participants are not aware of their exposure or outcome status?
a) Selection bias
b) Information bias
c) Confounding bias
d) Recall bias

93. What is the purpose of a confidence interval in hypothesis testing?
a) To determine the effect size of the study
b) To assess the normality of the distribution
c) To estimate the population parameters
d) To provide a range of values within which the true population parameter is likely to lie

94. Which statistical test is used to compare means between two independent groups with non-normal distributions or small sample sizes?
a) T-test
b) Chi-square test
c) Mann-Whitney U test
d) Wilcoxon signed-rank test

95. What does the term “interquartile range (IQR)” represent in statistics?
a) The average value of a dataset
b) The spread or dispersion of data points around the mean
c) The difference between the highest and lowest values in a dataset
d) The range of values that fall within the middle 50% of a dataset

96. Which type of study design is best suited for investigating the incidence of a disease in a specific population over time?
a) Cross-sectional study
b) Case-control study
c) Cohort study
d) Randomized controlled trial

97. What is the purpose of a paired t-test?
a) To compare the means of two independent groups
b) To compare the means of two paired groups
c) To compare the variances of two independent groups
d) To compare the proportions of two independent groups

98. Which statistical test is used to analyze the association between a continuous variable and a categorical variable with two levels?
a) T-test
b) Chi-square test
c) ANOVA
d) Linear regression analysis

99. In a randomized controlled trial, what is the purpose of blinding the participants and researchers?
a) To ensure all participants receive the same treatment
b) To provide a reference point for comparison
c) To minimize bias and confounding variables
d) To maximize the placebo effect

100. Which measure of dispersion is resistant to extreme values and outliers in a dataset?
a) Range
b) Variance
c) Interquartile range (IQR)
d) Standard deviation