PBSI 245 UNIT 1 EXAM QUESTIONS AND
ANSWERS GRADED A+ 2025/2026
Population - ANS The entire group of individuals about which information is sought.
Sample - ANS A subset of the population, selected for study.
Variable - ANS A characteristic or property that can take on different values for different
individuals.
Observational Study - ANS Researchers observe and record data without intervening.
Experimental Study - ANS Researchers impose a treatment to observe its effect.
Bias - ANS Systematic favoritism of certain outcomes over others in a study.
Convenience Sample - ANS Choosing individuals who are easiest to reach; often biased.
Voluntary Response Sample - ANS Individuals choose themselves to participate, often leading
to bias.
Simple Random Sample (SRS) - ANS Every individual and every possible sample has an equal
chance of being selected.
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, Sampling Frame - ANS The list from which a sample is actually selected.
Table of Random Digits - ANS A tool used to select random samples, where each digit is
equally likely and independent of other digits.
Parameter - ANS A number that describes a population (often unknown in practice).
Statistic - ANS A number that describes a sample; used to estimate population parameters.
Sampling Variability - ANS The idea that statistics can vary from sample to sample.
Bias (Sampling) - ANS Systematic deviation of a statistic from the parameter in the same
direction.
Variability - ANS How spread out the values of a statistic are when repeated samples are
taken.
Proportion - ANS The percentage of individuals in a group with a certain characteristic; in
samples, this is denoted as p̂ ('p-hat').
Margin of Error (MOE) - ANS Quantifies the uncertainty in an estimate, showing how much a
statistic would vary from sample to sample.
Confidence Interval - ANS A range of values that likely contains the true population
parameter, with a certain level of confidence (e.g., 95%).
Confidence Level - ANS The probability that the confidence interval contains the true
parameter (commonly 90%, 95%, or 99%).
Reduce bias - ANS Use random sampling methods.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
ANSWERS GRADED A+ 2025/2026
Population - ANS The entire group of individuals about which information is sought.
Sample - ANS A subset of the population, selected for study.
Variable - ANS A characteristic or property that can take on different values for different
individuals.
Observational Study - ANS Researchers observe and record data without intervening.
Experimental Study - ANS Researchers impose a treatment to observe its effect.
Bias - ANS Systematic favoritism of certain outcomes over others in a study.
Convenience Sample - ANS Choosing individuals who are easiest to reach; often biased.
Voluntary Response Sample - ANS Individuals choose themselves to participate, often leading
to bias.
Simple Random Sample (SRS) - ANS Every individual and every possible sample has an equal
chance of being selected.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Sampling Frame - ANS The list from which a sample is actually selected.
Table of Random Digits - ANS A tool used to select random samples, where each digit is
equally likely and independent of other digits.
Parameter - ANS A number that describes a population (often unknown in practice).
Statistic - ANS A number that describes a sample; used to estimate population parameters.
Sampling Variability - ANS The idea that statistics can vary from sample to sample.
Bias (Sampling) - ANS Systematic deviation of a statistic from the parameter in the same
direction.
Variability - ANS How spread out the values of a statistic are when repeated samples are
taken.
Proportion - ANS The percentage of individuals in a group with a certain characteristic; in
samples, this is denoted as p̂ ('p-hat').
Margin of Error (MOE) - ANS Quantifies the uncertainty in an estimate, showing how much a
statistic would vary from sample to sample.
Confidence Interval - ANS A range of values that likely contains the true population
parameter, with a certain level of confidence (e.g., 95%).
Confidence Level - ANS The probability that the confidence interval contains the true
parameter (commonly 90%, 95%, or 99%).
Reduce bias - ANS Use random sampling methods.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
