1. Sampling is defined as:
A. Studying every individual in a population
B. Selecting some members of a population to represent the entire population
C. Measuring only diseased individuals
D. Randomly selecting hospitals only
Answer: B
2. Sampling is mainly required when:
A. The population is very small
B. The population is very large and quick information is needed
C. No research question exists
D. Laboratory experiments are performed
Answer: B
3. The primary objective of sampling is to obtain:
A. A biased estimate
B. A representative subset of the population
C. A larger sample size
D. More variables
Answer: B
4. A sample is:
A. The entire target population
B. A subset selected from the population
C. Only hospitalized patients
D. A research hypothesis
Answer: B
5. The study population is:
A. The people selected into the sample
B. The population to which the study results will be generalized
C. The hospital where the study is conducted
D. Only healthy individuals
Answer: B
6. The study population depends primarily on:
A. Sample size
B. Research question
C. Available budget
D. Investigator preference
Answer: B
7. If the research question is, “How many injections do people receive each year in India?” the study population is:
A. Hospitals of India
B. Healthcare workers of India
C. Entire population of India
D. Children only
Answer: C
8. If the research question concerns needle-stick injuries among healthcare workers, the study population is:
A. General population
B. Hospitals only
C. Healthcare workers
D. Patients only
Answer: C
9. When studying hospitals with needle-stick prevention policies, the study population is:
A. Doctors
B. Nurses
C. Hospitals
D. Medical students
Answer: C
10. A representative sample should reflect the population with respect to:
A. Time only
B. Place only
C. Persons only
D. Time, place, and demographic characteristics
Answer: D
11. Representativeness with respect to time includes:
A. Urban and rural areas
B. Season, day of the week, and time of the day
C. Age and sex only
D. Income only
Answer: B
12. Representativeness with respect to place includes:
A. Urban and rural distribution
B. Blood groups
C. Education level
D. Occupation
Answer: A
13. Representativeness with respect to persons includes matching:
A. Temperature and humidity
B. Age, sex, and demographic characteristics
C. Income only
D. Religion only
Answer: B
14. A Sampling Unit (Basic Sampling Unit, BSU) is:
A. A statistical formula
B. The elementary unit selected for sampling
C. A sampling error
D. A sampling interval
Answer: B
15. Which of the following may serve as a sampling unit?
A. Person
B. Healthcare worker
C. Hospital
D. All of the above
Answer: D
16. A Sampling Frame is:
A. A statistical test
B. A list of all sampling units in the population
C. The study protocol
D. A sampling error
Answer: B
17. A Sampling Scheme refers to:
A. The research hypothesis
B. The method used to select sampling units from the sampling frame
C. The study design
D. The study objective
Answer: B
18. Which of the following is NOT a sampling term discussed in the lecture?
A. Sampling Unit
B. Sampling Frame
C. Sampling Scheme
D. Odds Ratio
Answer: D
19. Which is a major reason for using sampling instead of studying the whole population?
A. It always eliminates bias.
B. It is often more efficient and practical.
C. It guarantees perfect accuracy.
D. It removes sampling error.
Answer: B
20. Studying the entire population may be difficult mainly because of:
A. Lack of diseases
B. Time and resource constraints
C. Small sample size
D. Statistical software limitations
Answer: B
21. Collecting information from an extremely large population using many observers may increase:
A. Precision only
B. Inter-observer variation
C. Randomization
D. Blinding
Answer: B
22. Compared with complete population surveys, well-designed sample surveys often provide:
A. Less accurate information
B. More accurate information due to better quality control
C. No useful information
D. Only qualitative data
Answer: B
23. Which statement about population and sample is TRUE?
A. Population and sample are always identical.
B. A sample is selected to represent the population.
C. Every study requires complete enumeration.
D. A sample is always larger than the population.
Answer: B
24. The success of a sampling study depends mainly on:
A. Selecting the largest possible sample
B. Selecting a representative sample
C. Using only hospitals
D. Collecting only quantitative data
Answer: B
25. Which statement BEST summarizes the basic concepts of sampling?
A. Sampling is the process of selecting a representative subset of a population to obtain reliable information efficiently. The study population is determined by the research question, and an ideal sample should accurately represent the population with respect to time, place, and demographic characteristics. Key sampling terms include the sampling unit, sampling frame, and sampling scheme, all of which are fundamental for conducting valid biomedical research.
B. Sampling means selecting only convenient participants, regardless of the study objective.
C. The study population and sample are always identical, and representativeness is unnecessary.
D. Sampling is useful only when studying small populations.
Answer: A
BCBR Mock Test – Lecture 11
Sampling Methods
Part 2 (MCQ 26–50) – High-Level BCBR Questions
26. The Ministry of Health wants to estimate childhood immunization coverage within one month. What is the most practical approach?
A. Study the entire population
B. Conduct a sample survey
C. Study only one district
D. Conduct laboratory experiments
Answer: B
27. Which of the following is the major objective of sampling?
A. Increase disease prevalence
B. Obtain information efficiently from a large population
C. Eliminate sampling error
D. Replace statistics
Answer: B
28. Samples are broadly classified into:
A. Descriptive and Analytical
B. Experimental and Observational
C. Probability and Non-probability
D. Qualitative and Quantitative
Answer: C
29. In a Non-probability sample, the probability of selection is:
A. Equal for every individual
B. Known
C. Unknown
D. Always 50%
Answer: C
30. Which of the following is an example of Non-probability sampling?
A. Simple random sampling
B. Stratified sampling
C. Convenience sampling
D. Cluster sampling
Answer: C
31. Convenience sampling involves selecting participants based on:
A. Random numbers
B. Ease of access
C. Probability proportional to size
D. Stratification
Answer: B
32. Which is the greatest limitation of convenience sampling?
A. High cost
B. Selection bias
C. Difficult implementation
D. Requires a sampling frame
Answer: B
33. Convenience sampling may produce:
A. Highly representative samples
B. Best-case or worst-case scenarios
C. Perfect randomization
D. Zero sampling error
Answer: B
34. Subjective (purposive) sampling is mainly based on:
A. Lottery method
B. Investigator’s knowledge and judgment
C. Random numbers
D. Computer-generated selection
Answer: B
35. Non-probability sampling is commonly used to:
A. Estimate national prevalence accurately
B. Generate hypotheses
C. Measure sampling error precisely
D. Conduct randomized trials
Answer: B
36. Which statement regarding Non-probability sampling is TRUE?
A. Every participant has an equal chance of selection.
B. Sampling probability is known.
C. It is useful for preliminary or exploratory studies.
D. It eliminates selection bias.
Answer: C
37. In a Probability sample, every unit has:
A. Unknown probability of selection
B. Equal disease risk
C. A known probability of being selected
D. The same outcome
Answer: C
38. Which sampling method allows researchers to draw valid conclusions about the entire population?
A. Convenience sampling
B. Purposive sampling
C. Probability sampling
D. Snowball sampling
Answer: C
39. Which statement best describes probability sampling?
A. Selection depends entirely on investigator preference.
B. Every unit has a known probability of selection.
C. It is always cheaper than convenience sampling.
D. It cannot be used in biomedical research.
Answer: B
40. Random sampling in probability sampling primarily helps to:
A. Increase prevalence
B. Remove selection bias
C. Increase sample size
D. Eliminate measurement error
Answer: B
41. Random sampling ensures that each participant has:
A. An equal disease risk
B. A known probability of selection
C. The same characteristics
D. Equal income
Answer: B
42. Why is random sampling important for statistical analysis?
A. It increases sample size.
B. Most statistical methods assume random sampling.
C. It eliminates confounding.
D. It guarantees perfect accuracy.
Answer: B
43. Sampling error occurs because:
A. The entire population is studied.
B. A sample is not a perfect mirror of the population.
C. Every sample is biased.
D. Random sampling fails.
Answer: B
44. In probability sampling, the magnitude of sampling error can be estimated using:
A. Relative risk
B. Standard error
C. Odds ratio
D. Hazard ratio
Answer: B
45. Sampling error is influenced mainly by:
A. Sample size and variability
B. Age and sex
C. Disease prevalence only
D. Study design only
Answer: A
46. Increasing the sample size generally results in:
A. Larger sampling error
B. Smaller sampling error
C. No change in sampling error
D. Increased bias
Answer: B
47. Which statement regarding sampling error is TRUE?
A. It occurs only in non-probability sampling.
B. It can be quantified in probability sampling.
C. It cannot be measured.
D. It is identical to selection bias.
Answer: B
48. Which factor does NOT directly influence sampling error?
A. Sample size
B. Variability in measurements
C. Probability sampling
D. Hair color of participants
Answer: D
49. Which statement best distinguishes probability sampling from non-probability sampling?
A. Probability sampling uses investigator judgment only.
B. Probability sampling provides known selection probabilities and supports statistical inference.
C. Non-probability sampling always produces representative samples.
D. Both methods provide identical scientific validity.
Answer: B
50. Which statement BEST summarizes types of sampling and sampling error?
A. Sampling methods are broadly classified into probability and non-probability sampling. Non-probability sampling has an unknown chance of selection and is mainly useful for exploratory studies and hypothesis generation, whereas probability sampling gives every unit a known probability of selection, allowing valid statistical inference. Since a sample is never a perfect reflection of the population, sampling error is inevitable but can be estimated in probability sampling using standard error and is influenced primarily by sample size and variability.
B. Non-probability sampling is always superior because it completely eliminates sampling error.
C. Sampling error occurs only when convenience sampling is used and cannot be estimated in probability sampling.
D. Probability and non-probability sampling are identical methods that provide the same level of scientific evidence.
Answer: A
51. Which of the following is the first probability sampling method discussed in the lecture?
A. Cluster sampling
B. Stratified sampling
C. Simple Random Sampling
D. Multistage sampling
Answer: C
52. The basic principle of Simple Random Sampling (SRS) is that:
A. Every individual has an equal chance of being selected.
B. Only hospitals are selected.
C. Participants are selected based on convenience.
D. Population is divided into strata.
Answer: A
53. In Simple Random Sampling, participants are selected by:
A. Investigator judgment
B. Random selection after numbering all sampling units
C. Choosing every 10th individual
D. Selecting only volunteers
Answer: B
54. Which of the following is an advantage of Simple Random Sampling?
A. No sampling frame is required.
B. Sampling error is easily measured.
C. It always guarantees perfect representation.
D. It is free from all types of error.
Answer: B
55. The major limitation of Simple Random Sampling is that:
A. It requires no sampling frame.
B. A complete list of sampling units is required.
C. It cannot be used in biomedical research.
D. It always produces biased samples.
Answer: B
56. Even after Simple Random Sampling, the selected sample may:
A. Always perfectly represent the population.
B. Differ from the population due to chance.
C. Eliminate sampling error.
D. Never require statistical analysis.
Answer: B
57. Which probability sampling method selects an initial random unit followed by every kth unit?
A. Cluster Sampling
B. Stratified Sampling
C. Systematic Sampling
D. Convenience Sampling
Answer: C
58. In Systematic Sampling, the sampling interval (k) is calculated as:
A. Sample Size ÷ Population Size
B. Population Size ÷ Sample Size
C. Population Size × Sample Size
D. Sample Size − Population Size
Answer: B
59. The first participant in Systematic Sampling is selected:
A. By convenience
B. Randomly from the first k units
C. By investigator choice
D. From the last unit
Answer: B
60. After selecting the first participant in Systematic Sampling, subsequent participants are selected:
A. Randomly
B. Every kth unit
C. Every second unit
D. By lottery each time
Answer: B
61. Which is an important advantage of Systematic Sampling?
A. No planning is required.
B. It is easy to implement and provides good coverage of the sampling list.
C. It removes all bias.
D. No sampling interval is needed.
Answer: B
62. Systematic Sampling may become problematic when:
A. The population is small.
B. The sampling list has periodic patterns or cycles.
C. Random numbers are used.
D. The sample size is large.
Answer: B
63. Which probability sampling method divides the population into homogeneous groups before sampling?
A. Cluster Sampling
B. Stratified Sampling
C. Convenience Sampling
D. Simple Random Sampling
Answer: B
64. In Stratified Sampling, homogeneous subgroups are called:
A. Clusters
B. Blocks
C. Strata
D. Frames
Answer: C
65. After dividing the population into strata, researchers:
A. Study only one stratum.
B. Draw samples from each stratum.
C. Ignore the strata.
D. Use convenience sampling.
Answer: B
66. Which is a major advantage of Stratified Sampling?
A. It requires no planning.
B. All important subgroups are represented.
C. No sampling frame is required.
D. Sampling error is eliminated.
Answer: B
67. Stratified Sampling generally provides:
A. Lower precision
B. Greater precision when the variable is related to the strata
C. Higher sampling error
D. No subgroup estimates
Answer: B
68. Which is a limitation of Stratified Sampling?
A. Sampling error is difficult to measure.
B. It cannot estimate subgroup characteristics.
C. It does not improve representativeness.
D. Random selection is impossible.
Answer: A
69. Precision in Stratified Sampling may decrease when:
A. The number of strata is reduced.
B. Very few participants are selected from each stratum.
C. Equal allocation is used.
D. Random sampling is performed.
Answer: B
70. Which of the following is an example of Stratified Sampling?
A. Selecting every 10th house.
B. Dividing a country into North, South, East, and West regions and sampling each region.
C. Selecting one village randomly.
D. Choosing nearby participants.
Answer: B
71. Which probability sampling method is generally easiest to understand and implement?
A. Multistage Sampling
B. Cluster Sampling
C. Simple Random Sampling
D. Stratified Sampling
Answer: C
72. Which probability sampling method provides better representation across an ordered sampling list?
A. Convenience Sampling
B. Systematic Sampling
C. Cluster Sampling
D. Purposive Sampling
Answer: B
73. Which probability sampling method is particularly useful when important subgroups must all be represented?
A. Cluster Sampling
B. Stratified Sampling
C. Simple Random Sampling
D. Snowball Sampling
Answer: B
74. Which statement correctly compares the three probability sampling methods?
A. Simple Random Sampling requires a sampling frame; Systematic Sampling selects every kth unit after a random start; Stratified Sampling samples separately from each homogeneous stratum.
B. All three methods use convenience sampling.
C. None require a sampling frame.
D. All three eliminate sampling error.
Answer: A
75. Which statement BEST summarizes Simple Random, Systematic, and Stratified Sampling?
A. Simple Random Sampling gives every unit an equal chance of selection but requires a complete sampling frame. Systematic Sampling selects every kth unit after a random start and is easy to implement but may be affected by periodic patterns. Stratified Sampling divides the population into homogeneous strata, samples each stratum separately, and usually provides greater precision and better representation of important subgroups, although sampling error may be more difficult to estimate when many small strata are created.
B. All three sampling methods use convenience selection and produce identical results.
C. Systematic Sampling completely eliminates sampling error, whereas Stratified Sampling cannot be used in health research.
D. Simple Random Sampling, Systematic Sampling, and Stratified Sampling are non-probability sampling methods.
Answer: A
76. Which probability sampling method selects groups (clusters) rather than individual subjects?
A. Simple Random Sampling
B. Systematic Sampling
C. Cluster Sampling
D. Stratified Sampling
Answer: C
77. In Cluster Sampling, the sampling unit is:
A. An individual participant
B. A household member only
C. A group or cluster of subjects
D. A hospital bed
Answer: C
78. Which of the following is an advantage of Cluster Sampling?
A. Requires a complete list of all individuals
B. Less travel and fewer resources are required
C. Eliminates sampling error
D. Provides the highest precision in every situation
Answer: B
79. Which is a major limitation of Cluster Sampling?
A. It cannot be used in health surveys.
B. Sampling error is often difficult to measure.
C. Every participant has an unknown probability of selection.
D. It requires studying the entire population.
Answer: B
80. Cluster Sampling is particularly useful when:
A. A complete list of individuals is unavailable.
B. Only laboratory data are collected.
C. The population is very small.
D. Only qualitative research is conducted.
Answer: A
81. Cluster Sampling assumes that:
A. Variability within each cluster reflects that of the general population.
B. Every cluster is identical.
C. All participants have the same disease.
D. Sampling error does not occur.
Answer: A
82. In Cluster Sampling, variability between clusters should ideally be:
A. Very high
B. Minimal
C. Unknown
D. Equal to zero
Answer: B
83. Cluster Sampling is commonly performed using:
A. A two-stage approach
B. Convenience sampling
C. Purposive sampling
D. Census enumeration
Answer: A
84. In the first stage of Cluster Sampling, clusters are commonly selected using:
A. Lottery without probability
B. Probability Proportional to Size (PPS)
C. Purposive selection
D. Convenience sampling
Answer: B
85. After clusters are selected, the second stage usually involves:
A. Studying the whole country
B. Selecting a random sample within each cluster
C. Selecting another cluster
D. Ignoring the selected clusters
Answer: B
86. Which sampling method is most suitable for large national health surveys involving villages or districts?
A. Convenience Sampling
B. Cluster Sampling
C. Snowball Sampling
D. Consecutive Sampling
Answer: B
87. Multistage Sampling is based on:
A. One-stage random selection only
B. Several sequential stages of sampling
C. Convenience sampling followed by purposive sampling
D. Census of the entire population
Answer: B
88. Which is a major advantage of Multistage Sampling?
A. No sampling frame is required at any stage.
B. It is practical and feasible for very large populations.
C. It completely removes sampling error.
D. It always has the highest precision.
Answer: B
89. Which is a limitation of Multistage Sampling?
A. Only one sampling unit is used.
B. Sampling error may be difficult to estimate.
C. It cannot be used for national surveys.
D. It always requires convenience sampling.
Answer: B
90. Which probability sampling method is MOST appropriate for nationwide demographic or health surveys?
A. Convenience Sampling
B. Purposive Sampling
C. Multistage Sampling
D. Consecutive Sampling
Answer: C
91. A researcher wants to estimate vaccination coverage across an entire country by selecting districts, then villages, and finally households. Which sampling method is most appropriate?
A. Simple Random Sampling
B. Stratified Sampling
C. Multistage Sampling
D. Systematic Sampling
Answer: C
92. Which statement regarding probability sampling is CORRECT?
A. It allows valid statistical inference because selection probabilities are known.
B. It always eliminates sampling error.
C. It requires investigator judgment only.
D. It cannot estimate population parameters.
Answer: A
93. Which of the following statements about sampling error is TRUE?
A. It occurs because a sample is not a perfect mirror of the population.
B. It exists only in convenience sampling.
C. It cannot be estimated.
D. It is identical to measurement bias.
Answer: A
94. According to the lecture, good study design and quality assurance primarily improve:
A. Sample size
B. Validity
C. Disease prevalence
D. Random error
Answer: B
95. Appropriate sample size primarily improves:
A. Validity
B. Precision
C. Convenience
D. Bias
Answer: B
96. Which sampling approach permits the application of most statistical tests?
A. Non-probability Sampling
B. Convenience Sampling
C. Probability Sampling
D. Purposive Sampling
Answer: C
97. A researcher selects every 10th household after choosing a random starting house. Which sampling method is being used?
A. Cluster Sampling
B. Stratified Sampling
C. Systematic Sampling
D. Multistage Sampling
Answer: C
98. A nationwide health survey divides the country into North, South, East, and West regions and randomly samples from each region before combining the results. Which sampling method is illustrated?
A. Cluster Sampling
B. Stratified Sampling
C. Simple Random Sampling
D. Convenience Sampling
Answer: B
99. Which sampling method would be MOST appropriate if investigators have no complete list of individuals but can identify villages as groups?
A. Simple Random Sampling
B. Cluster Sampling
C. Convenience Sampling
D. Purposive Sampling
Answer: B
100. Which statement BEST summarizes Sampling Methods?
A. Sampling is the process of selecting a representative subset of a population for research. Non-probability sampling is mainly useful for exploratory studies and hypothesis generation, whereas probability sampling allows valid statistical inference because every unit has a known probability of selection. Major probability sampling methods include Simple Random, Systematic, Stratified, Cluster, and Multistage Sampling, each with specific principles, advantages, and limitations. A well-designed representative sample, appropriate sample size, and quality assurance improve the validity and precision of research findings while minimizing sampling error.
B. Convenience sampling is always the preferred method because it completely removes sampling error and provides the most representative sample.
C. Probability sampling and non-probability sampling provide identical scientific validity and can always be used interchangeably.
D. Sampling methods are unnecessary because every biomedical study should include the entire population.
Answer: A
