1. What is the primary purpose of selecting an appropriate study population in health research?
A. To reduce publication time
B. To ensure the findings accurately represent the population of interest
C. To reduce the study duration
D. To increase the number of variables
Answer: B
2. According to the lecture, which of the following is one of the three important considerations while selecting study subjects?
A. Publishing in a high-impact journal
B. Selecting subjects at an acceptable cost
C. Increasing the number of investigators
D. Conducting only hospital-based studies
Answer: B
3. An adequate study population primarily helps to:
A. Increase funding
B. Control random error
C. Improve publication chances
D. Eliminate confounding
Answer: B
4. A representative study population is essential because it allows the findings to be:
A. Published quickly
B. Generalized to the population of interest
C. Collected at low cost
D. Analyzed without statistics
Answer: B
5. Which topic is specifically NOT covered in this lecture?
A. Sampling techniques
B. Selection of study population
C. Representativeness
D. Recruitment strategies
Answer: A
6. In research terminology, a population refers to:
A. Only hospital patients
B. A larger group from which study participants are selected
C. Only healthy individuals
D. Individuals enrolled in a clinical trial
Answer: B
7. A target population is defined mainly by:
A. Clinical and demographic characteristics
B. Geographic location only
C. Sampling method
D. Sample size
Answer: A
8. Which of the following best describes an accessible population?
A. The entire country’s population
B. A subset of the target population defined by geographical and temporal characteristics
C. All hospital admissions
D. Only participants who complete the study
Answer: B
9. A study sample is:
A. The entire target population
B. A subset selected from the accessible population
C. All eligible participants worldwide
D. Every patient visiting a hospital
Answer: B
10. Which characteristic mainly defines the accessible population?
A. Age and gender
B. Clinical diagnosis only
C. Geographical and temporal characteristics
D. Income level
Answer: C
11. In the lecture example on PCOS, the target population consisted of:
A. All women in India
B. Females with PCOS in the reproductive age group suffering from dysmenorrhea
C. All hospital patients
D. Women attending any outpatient department
Answer: B
12. In the same example, the accessible population included:
A. Women from every hospital in India
B. Patients attending the investigator’s OPD during the specified period
C. Every female in the community
D. All diabetic patients
Answer: B
13. Which characteristic determines the time period during which participants are recruited?
A. Clinical characteristic
B. Demographic characteristic
C. Temporal characteristic
D. Biological characteristic
Answer: C
14. Which sequence correctly represents the process of selecting study participants?
A. Study Sample → Accessible Population → Population → Target Population
B. Population → Target Population → Accessible Population → Study Sample
C. Target Population → Population → Study Sample → Accessible Population
D. Population → Study Sample → Target Population → Accessible Population
Answer: B
15. The research question primarily helps define the:
A. Journal
B. Target population
C. Sample size only
D. Statistical software
Answer: B
16. Internal validity refers to:
A. Generalizing findings to other populations
B. The degree to which study findings are valid within the study itself
C. Study funding
D. Sample size estimation
Answer: B
17. External validity is also known as:
A. Randomization
B. Generalizability
C. Precision
D. Accuracy
Answer: B
18. External validity refers to the ability to:
A. Recruit participants
B. Apply study findings to the population of interest
C. Calculate sample size
D. Perform statistical analysis
Answer: B
19. According to the lecture, good internal validity is:
A. Unimportant
B. Essential before generalizing results
C. Only required in laboratory studies
D. Possible only in descriptive studies
Answer: B
20. Random error during subject selection can be reduced primarily by:
A. Increasing publication quality
B. Increasing the sample size
C. Changing the study design
D. Using convenience sampling
Answer: B
21. Which statement about representative samples is TRUE?
A. They never experience bias.
B. They help ensure study findings represent the population of interest.
C. They eliminate confounding.
D. They require no inclusion criteria.
Answer: B
22. Which validity is most directly related to applying study findings to a wider population?
A. Internal validity
B. External validity
C. Face validity
D. Construct validity
Answer: B
23. Which of the following best defines a study sample?
A. Every member of the target population
B. Individuals selected from the accessible population for research
C. Every patient attending the hospital
D. Only healthy volunteers
Answer: B
24. Which statement regarding target and accessible populations is CORRECT?
A. They always represent the same group.
B. The accessible population is a subset of the target population.
C. The target population is selected after sampling.
D. The study sample is larger than the target population.
Answer: B
25. Which statement BEST summarizes the concepts covered in this section?
A. Selection of a study population begins with defining the population of interest, followed by identifying the target population using clinical and demographic characteristics. An accessible population is then defined using geographical and temporal characteristics, from which a representative study sample is selected. Adequate sample size controls random error, while representative sampling improves the generalizability and validity of research findings.
B. The target population and study sample are always identical, making sampling unnecessary.
C. Accessible population is selected only after statistical analysis.
D. Internal validity depends only on the sample size and not on subject selection.
Answer: A
BCBR Mock Test – Lecture 13
Selection of Study Population
Part 2 (MCQ 26–50) – Moderate to High-Level Questions
26. Which validity primarily reflects the degree to which the observed results are true within the study participants?
A. External validity
B. Ecological validity
C. Internal validity
D. Face validity
Answer: C
27. Internal validity mainly assesses whether:
A. Findings can be generalized worldwide.
B. The dependent variable is influenced by the independent variable within the study.
C. The sample size is adequate.
D. Participants belong to different populations.
Answer: B
28. External validity refers to:
A. Accuracy of laboratory instruments
B. Ability to generalize study findings to the target population
C. Statistical significance
D. Randomization
Answer: B
29. According to the lecture, which validity should be established before attempting to generalize findings?
A. Ecological validity
B. Construct validity
C. Internal validity
D. Predictive validity
Answer: C
30. The “truth in the study” is inferred from:
A. The target population
B. The actual study subjects and measurements
C. The accessible population only
D. The literature review
Answer: B
31. The “truth in the universe” represents:
A. Findings applicable to the population of interest
B. Study protocol
C. Laboratory measurements
D. Pilot study results
Answer: A
32. During subject selection, random errors can primarily be reduced by:
A. Using purposive sampling
B. Increasing the sample size
C. Increasing the study duration
D. Reducing the number of variables
Answer: B
33. Which statement about internal validity is TRUE?
A. It guarantees external validity.
B. It is essential for reliable study conclusions.
C. It depends only on sample size.
D. It is important only in descriptive studies.
Answer: B
34. According to the lecture, there is always a trade-off between:
A. Sample size and budget
B. Internal validity and generalizability
C. Alpha and beta
D. Sensitivity and specificity
Answer: B
35. Representative samples are generally more prone to:
A. Laboratory error
B. Bias and confounding than highly controlled internally valid samples
C. Randomization error only
D. Publication bias
Answer: B
36. Which statement best describes internally valid studies?
A. Their findings are always generalizable.
B. They are never affected by bias.
C. Their findings may not always be generalizable to the target population.
D. They require community-based sampling only.
Answer: C
37. Generalizability is influenced by:
A. Study design
B. Research methods
C. Nature of the findings
D. All of the above
Answer: D
38. According to the lecture, generalizable results are more commonly obtained from:
A. Analytical studies and clinical trials
B. Case reports only
C. Cross-sectional surveys only
D. Laboratory experiments only
Answer: A
39. Descriptive studies mainly describe:
A. Cause-effect relationships
B. Distribution of characteristics within a population
C. Drug efficacy
D. Genetic inheritance
Answer: B
40. Why are descriptive study findings often difficult to generalize?
A. They include too many participants.
B. They primarily describe characteristics of the specific study population.
C. They never use statistics.
D. They always have small sample sizes.
Answer: B
41. The Framingham Cohort Study was used in the lecture to illustrate:
A. Sample size calculation
B. Generalizability of study findings
C. Laboratory diagnosis
D. Randomization
Answer: B
42. Which finding from the Framingham Cohort Study was considered generalizable?
A. Exact prevalence of hypertension
B. Association between cardiovascular risk factors and disease
C. Hospital admission rates
D. Local demographic distribution
Answer: B
43. Which of the following may NOT be generalizable according to the Framingham example?
A. Association of hypertension with cardiovascular disease
B. Exact prevalence of hypertension in different ethnic groups
C. Biological mechanisms of disease
D. Clinical diagnosis
Answer: B
44. Inclusion criteria primarily define:
A. Individuals who should participate in the study
B. Statistical tests
C. Sample size
D. Funding requirements
Answer: A
45. Inclusion criteria are mainly based on:
A. Research question and target population characteristics
B. Journal requirements
C. Investigator’s preference
D. Budget only
Answer: A
46. Exclusion criteria identify participants who:
A. Best represent the study population
B. May interfere with follow-up, data quality, or ethical conduct of the study
C. Increase statistical power
D. Improve randomization
Answer: B
47. Which of the following may be a reason for excluding participants from a study?
A. High likelihood of loss to follow-up
B. Poor quality of data
C. Ethical concerns
D. All of the above
Answer: D
48. The primary purpose of exclusion criteria is to:
A. Increase the target population
B. Improve the quality, feasibility, and validity of the study
C. Increase disease prevalence
D. Eliminate the need for sampling
Answer: B
49. After applying inclusion and exclusion criteria, researchers obtain the:
A. Entire target population
B. Final study sample from the accessible population
C. General population
D. Census population
Answer: B
50. Which statement BEST summarizes the concepts of validity, generalizability, and selection criteria?
A. Internal validity reflects the accuracy of findings within the study population, whereas external validity refers to the ability to generalize findings to the target population. There is often a trade-off between these two concepts. Appropriate inclusion criteria define who should be enrolled, while exclusion criteria remove individuals who may compromise follow-up, data quality, ethical conduct, or study validity, resulting in a representative and scientifically sound study sample.
B. Internal validity automatically guarantees external validity, so inclusion and exclusion criteria are unnecessary.
C. Generalizability depends only on sample size and not on study design or participant selection.
D. Exclusion criteria are used only to reduce study costs and have no effect on study quality.
Answer: A
51. In a clinical trial, inclusion criteria are primarily designed to:
A. Increase publication chances
B. Select participants relevant to the research question
C. Reduce the study duration
D. Eliminate statistical analysis
Answer: B
52. In the lecture example of a metformin trial, which demographic characteristic formed part of the inclusion criteria?
A. All adult males
B. Females aged 15–44 years
C. Children below 10 years
D. Elderly women above 65 years
Answer: B
53. Which clinical characteristic was included in the metformin trial example?
A. Hypertension
B. Diabetes mellitus
C. Females with PCOS suffering from dysmenorrhea
D. Thyroid disease
Answer: C
54. Which geographical characteristic was used in the lecture example?
A. Patients from the entire country
B. Patients attending the hospital OPD in the study region
C. Patients from multiple continents
D. Home-based participants only
Answer: B
55. Which temporal characteristic was included in the example?
A. Recruitment throughout life
B. January 1 to December 31 of the specified year
C. One month only
D. Weekend recruitment only
Answer: B
56. Which participant was excluded because of a high likelihood of loss to follow-up?
A. A participant planning to move away during the study period
B. A healthy volunteer
C. A participant giving informed consent
D. A newly diagnosed patient
Answer: A
57. Patients already receiving metformin for another condition were excluded mainly because they could:
A. Increase sample size
B. Interfere with the quality of study data
C. Improve recruitment
D. Reduce study cost
Answer: B
58. Individuals with renal dysfunction were excluded because:
A. They increase statistical power.
B. They are at higher risk of adverse effects from metformin.
C. They cannot provide consent.
D. They belong to another target population.
Answer: B
59. Which source population is generally preferred when the research question involves patients with a disease?
A. Community population
B. Hospital or clinic-based population
C. School population
D. Census population
Answer: B
60. Community-based populations are particularly useful for studies involving:
A. Healthy individuals
B. Only hospitalized patients
C. Intensive care patients
D. Laboratory animals
Answer: A
61. Vaccine efficacy studies are commonly conducted using:
A. Hospital-based populations
B. Community-based populations
C. Laboratory workers only
D. Medical students only
Answer: B
62. One major disadvantage of community-based recruitment is that it is:
A. Scientifically invalid
B. Difficult and expensive
C. Unable to recruit healthy participants
D. Impossible to perform
Answer: B
63. According to the lecture, the choice between hospital-based and community-based populations depends mainly on:
A. Investigator preference
B. Research question
C. Publication requirements
D. Sample size only
Answer: B
64. Which factor is considered the most important while recruiting study participants?
A. Investigator experience
B. Feasibility
C. Journal selection
D. Sample coding
Answer: B
65. Feasibility influences:
A. Selection of the accessible population
B. Choice of sampling approach
C. Recruitment strategy
D. All of the above
Answer: D
66. One major goal of recruitment is to ensure that participants:
A. Adequately represent the target population
B. Increase disease prevalence
C. Reduce study duration
D. Eliminate random error
Answer: A
67. The second major goal of recruitment is to:
A. Recruit enough participants to meet the required sample size
B. Publish quickly
C. Increase statistical significance
D. Eliminate confounding
Answer: A
68. Achieving a representative sample begins during the:
A. Data analysis phase
B. Design phase
C. Publication phase
D. Peer review phase
Answer: B
69. During the design phase, researchers should mainly:
A. Choose the population and sampling methods wisely
B. Write the discussion section
C. Analyze the results
D. Prepare conference posters
Answer: A
70. During the implementation phase, researchers should monitor:
A. Journal citations
B. Participant adherence to selection criteria
C. Grant applications
D. Literature review
Answer: B
71. Non-response is generally more common in:
A. Clinical trials
B. Observational studies
C. Laboratory experiments
D. Animal studies
Answer: B
72. High non-response primarily affects:
A. Internal validity and generalizability
B. Sample labeling
C. Randomization sequence
D. Statistical software
Answer: A
73. Which strategy helps reduce non-response during a study?
A. Avoiding participant follow-up
B. Repeated contact attempts
C. Decreasing sample size
D. Removing informed consent
Answer: B
74. Which of the following can improve participant retention?
A. Providing translated questionnaires
B. Using bilingual interviewers
C. Minimizing participant discomfort
D. All of the above
Answer: D
75. Which statement BEST summarizes recruitment, representative sampling, and non-response?
A. A representative sample begins with careful planning during the design phase by selecting an appropriate accessible population and sampling method. During implementation, researchers ensure adherence to inclusion and exclusion criteria, recruit enough participants to meet the required sample size, and minimize non-response through repeated contact, participant-friendly study procedures, incentives, and bilingual or translated questionnaires. These measures improve internal validity, representativeness, and the generalizability of study findings.
B. Recruitment begins only after statistical analysis, and non-response has little effect on study validity.
C. Hospital-based populations are always superior to community-based populations regardless of the research question.
D. Non-response affects only sample size and has no influence on validity or generalizability.
Answer: A
76. A researcher wants to study the effectiveness of a new antihypertensive drug. Which source of study population is MOST appropriate?
A. School children
B. Hospital or clinic-based hypertensive patients
C. Healthy volunteers from the community
D. Census population
Answer: B
77. A researcher plans to evaluate vaccine effectiveness among healthy children in a district. Which source population is MOST suitable?
A. Intensive Care Unit patients
B. Community-based population
C. Hospital inpatients only
D. Laboratory workers
Answer: B
78. Which factor primarily determines whether a hospital-based or community-based population should be selected?
A. Sample size
B. Research question
C. Publication deadline
D. Investigator’s preference
Answer: B
79. During participant recruitment, feasibility mainly influences:
A. Choice of accessible population and sampling strategy
B. Statistical significance
C. Journal selection
D. Type of laboratory equipment
Answer: A
80. Which of the following BEST describes the first goal of recruitment?
A. Recruiting participants quickly
B. Recruiting subjects who adequately represent the target population
C. Recruiting only healthy volunteers
D. Recruiting equal numbers of males and females
Answer: B
81. Which of the following BEST describes the second goal of recruitment?
A. Minimizing publication bias
B. Recruiting enough participants to satisfy the required sample size
C. Reducing the study duration
D. Maximizing external funding
Answer: B
82. Achieving a representative sample begins during the:
A. Publication phase
B. Design phase
C. Statistical analysis phase
D. Peer-review phase
Answer: B
83. During the design phase, researchers should primarily:
A. Analyze the collected data
B. Select appropriate populations and sampling methods
C. Recruit additional investigators
D. Publish the protocol
Answer: B
84. During the implementation phase, researchers should primarily:
A. Modify the research question
B. Monitor adherence to selection criteria and participant follow-up
C. Increase the target population
D. Change inclusion criteria daily
Answer: B
85. Which situation BEST illustrates loss to follow-up?
A. A participant refuses to sign informed consent.
B. A participant relocates and cannot be contacted during follow-up.
C. A participant meets all inclusion criteria.
D. A participant completes every scheduled visit.
Answer: B
86. Non-response is generally more common in:
A. Randomized clinical trials
B. Observational studies
C. Laboratory experiments
D. Animal studies
Answer: B
87. High non-response primarily threatens:
A. Internal validity and generalizability
B. Statistical software
C. Ethical approval
D. Laboratory calibration
Answer: A
88. Which strategy is MOST effective for reducing non-response?
A. Recruiting fewer participants
B. Repeated contact attempts
C. Increasing the significance level
D. Removing follow-up visits
Answer: B
89. Which approach helps improve participant retention during a study?
A. Using complicated questionnaires
B. Designing procedures that minimize participant discomfort
C. Avoiding participant communication
D. Eliminating follow-up reminders
Answer: B
90. Which recruitment strategy is especially useful when participants speak different languages?
A. Randomization
B. Translated questionnaires and bilingual interviewers
C. Convenience sampling
D. Blinding
Answer: B
91. A researcher repeatedly contacts participants who initially did not respond to invitations. This strategy aims to reduce:
A. Recall bias
B. Non-response bias
C. Selection bias
D. Measurement error
Answer: B
92. A clinical trial excludes patients with severe renal disease because they are at increased risk from the study medication. This exclusion mainly addresses:
A. Ethical and participant safety concerns
B. Sample size calculation
C. Randomization
D. Publication bias
Answer: A
93. A researcher wants findings that are applicable to the general population. Which characteristic should receive the greatest emphasis?
A. Representativeness of the study sample
B. Low publication cost
C. Small sample size
D. Short follow-up duration
Answer: A
94. Which sequence correctly represents the overall process of selecting study participants?
A. Recruitment → Sampling → Inclusion Criteria → Target Population
B. Target Population → Accessible Population → Apply Exclusion Criteria → Sampling → Recruitment
C. Sampling → Accessible Population → Target Population → Recruitment
D. Recruitment → Target Population → Sampling → Exclusion Criteria
Answer: B
95. Which step immediately follows defining the target population?
A. Recruitment strategy
B. Defining the accessible population
C. Statistical analysis
D. Publication
Answer: B
96. Which step follows the application of exclusion criteria?
A. Literature review
B. Sampling using the selected sampling technique and estimated sample size
C. Writing the discussion
D. Ethical approval
Answer: B
97. In the final stage of selecting a study population, researchers should focus on:
A. Calculating prevalence
B. Recruiting adequate participants while minimizing non-response and loss to follow-up
C. Reducing confidence intervals
D. Revising the hypothesis
Answer: B
98. A researcher carefully defines inclusion criteria, excludes participants likely to have poor follow-up, uses an appropriate sampling method, and continuously monitors participant adherence throughout the study. This approach is MOST likely to improve:
A. Study validity and representativeness
B. Disease prevalence
C. Publication speed
D. Laboratory turnaround time
Answer: A
99. Which statement regarding selection of study population is CORRECT?
A. Representative sampling alone guarantees perfect internal validity.
B. Selection of study population is a stepwise process involving target population, accessible population, exclusion criteria, sampling, and recruitment.
C. Exclusion criteria are unnecessary if the sample size is large.
D. Recruitment begins before defining the target population.
Answer: B
100. Which statement BEST summarizes the lecture on Selection of Study Population?
A. Selection of a study population is a systematic process that begins with defining the target population through clinical and demographic characteristics, followed by identifying an accessible population using geographical and temporal criteria. Appropriate inclusion and exclusion criteria are applied to obtain a representative study sample. Sampling techniques and adequate sample size are then used to minimize random error, while effective recruitment strategies reduce non-response and loss to follow-up. Maintaining a balance between internal validity and external validity ensures that study findings are both scientifically valid and generalizable to the population of interest.
B. Hospital-based populations are always preferred because they automatically provide representative samples for every research question.
C. Internal validity guarantees external validity, so recruitment and follow-up are not important.
D. Selection of study population depends only on sample size, while inclusion criteria, exclusion criteria, recruitment, and representativeness have little effect on study quality.
Answer: A
