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Determinants of Survey Sample Size
The optimal sample size for a survey generally depends on two primary factors: the researcher's desired level of statistical confidence and the practical constraints of the study's budget. If the sampling design and other factors are held constant, larger samples reduce expected sampling error; they also require more time, effort, and money to collect. Increasing sample size alone does not remove systematic bias from an incomplete sampling frame (Statistics Canada, Chapter 8, sections 8.1–8.2.1). Researchers frequently use power analyses to balance these theoretical and practical considerations.
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Research Methods in Psychology - 4th American Edition @ KPU
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Relationship Between Sample and Population
A team of researchers wants to understand the typical sleep habits of all adults in a country of 50 million people. Since they cannot survey every individual, which of the following approaches would be the most practical and scientifically sound first step for their investigation?
Random Sample
Example of a Sample: Talkativeness Study
Representative Sample
Inferential Statistics
Probability Sampling
Non-probability Sampling
Determinants of Survey Sample Size
Convenience Sampling
Survey Non-responder
Simple Random Sampling
Sampling Bias
Measures of Central Tendency
Which of the following best explains why a psychology researcher would choose to study a sample rather than an entire population?
A researcher is investigating the exercise habits of all 5,000 employees at a corporate headquarters. Arrange the steps of the research process in the correct logical order to show how a sample is used to understand the entire group.
A psychologist investigates the study habits of all first-year college students by surveying 200 first-year students at a single university. Match each part of this study to its functional role in the sampling process.
A researcher concludes that a sample of 1,000 volunteers recruited from a specialized tech-support website is a methodologically sound group for evaluating the computer literacy of all adults in a nation. This conclusion is justified because a sample size this large () automatically guarantees that the subset will closely resemble the entire group of interest.
Imagine you are a researcher designing a study to assess the prevalence of academic burnout among the students in a statewide public university system. To construct a sampling plan that yields a highly representative subset () while ensuring that students from 'commuter', 'residential', and 'online-only' campuses are proportionally represented, which of the following sampling architectures should you create?
In psychological research, the primary goal of measuring variables in a sample is to generalize the findings back to the broader population of interest.
To conduct a study, researchers typically select a smaller subset of individuals from a broader group of interest. This smaller subset is referred to as a _____.
A psychology researcher wants to study the relationship between screen time and sleep quality among undergraduate students at a large university. Match each component of their study design to its corresponding concept in the sampling process.
A researcher measures academic anxiety in a group of 100 college students, intending to apply these results to all college students nationwide. In research methodology, the ultimate scientific goal of measuring these variables within a sample is to _____ the findings back to the broader population.
A researcher is planning a study on student stress. Evaluate and arrange the steps of the sampling and measurement process in the correct logical order, starting with the broadest scope and ending with the final application of the research findings.
In psychological research, what is a sample?
In psychological research, an investigator can confidently generalize the findings from a sample to the broader population of interest, regardless of whether the sample's characteristics resemble those of that population.
For each psychological research study, match the study's research description (which outlines the population of interest) with its corresponding sample (the actual subset of individuals from whom data was collected).
A researcher is studying academic anxiety levels within the population of 'all undergraduate psychology majors at KPU.' Analyze the following samples and arrange them in order from most representative (1) to least representative (3) of this target population.
A clinical psychologist conducts a study on stress levels among all working parents in a city, but collects data from a sample consisting entirely of high-income parents living in a single private community. In evaluating the generalizability of this study, the psychologist must conclude that this subset of parents is an ______ sample because its characteristics do not closely resemble those of the broader target population.
In scientific research, a sample refers to the entire, complete group of all individuals that a researcher wants to understand and draw conclusions about.
Which of the following statements best explains the scientific rationale for using a sample in psychological research?
A developmental psychologist wants to study the screen-time habits of all toddlers in a specific city. Since it is impossible to track every child, the researcher recruits and gathers data from 75 toddlers whose parents volunteered. In this study, the group of 75 toddlers represents the ______.
Analyze each of the following psychological research scenarios to evaluate the relationship between the defined population of interest and the obtained sample. Match each research scenario with its most accurate methodological evaluation.
Evaluating the generalizability of psychological research requires judging the scientific justification of a researcher's claims based on their sample and population. Evaluate the three research scenarios below and arrange them in order of their scientific generalizability, from the most justified generalization (first) to the least justified generalization (third).
In psychological research, what is a sample?
In psychological research, researchers measure variables within a sample with the intention of keeping their findings strictly limited to the individuals who directly participated in the study.
A researcher wants to study the effects of a new teaching method on the math performance of all 5th-grade students in a large school district. To do this, they randomly select three 5th-grade classrooms from one local school to participate in the study. Which of the following best analyzes the relationship between the sample and the population in this scenario?
In psychological research, why is it ideal for a sample to be representative of the population of interest?
A ______ is a smaller subset of individuals selected from a larger population of interest for the purpose of a research study.
A clinical psychologist evaluates a new therapy program for adolescents diagnosed with depression by testing it on 40 adolescent patients at a local clinic. In this research design, the 40 adolescent patients serve as the population of the study.
A research team wants to estimate the prevalence of generalized anxiety among all undergraduate students at a large university (the defined population). Evaluate the scientific justification for generalizing from the four distinct samples below. Match each sampling strategy to its most accurate methodological evaluation.
Learn After
Confidence Interval
Sample Size and Population Size
When determining the optimal sample size for a survey, what are the two primary factors a researcher must generally balance?
A psychology researcher is planning a survey to study community health habits. Match each factor involved in determining their sample size with the specific role it plays in the planning process.
A social psychologist planning a survey on community resilience determines that 900 participants are required to achieve their desired level of statistical confidence. However, after realizing that the recruitment costs for 900 people would exceed their $500 research grant, they decide to survey only 400 people. In this scenario, the researcher has prioritized the study's budget over their initial goal for statistical confidence.
A psychology researcher is planning a survey on community mental health. Arrange the following steps in the logical sequence required to analyze and balance the determinants of their study's sample size.
When determining survey sample size, researchers frequently use a power analysis to balance the desired level of statistical confidence with the practical constraints of their study's budget.
When planning a survey, a researcher must understand how sample size relates to both statistical confidence and practical constraints. Which statement best describes the trade-off a researcher faces when determining their survey's sample size?
A psychology researcher finds that increasing their survey sample from to participants would cost an additional $1,500 but only provide a negligible increase in statistical confidence. By deciding that the marginal gain in precision does not justify the extra expense, the researcher has performed a/an _____ of the trade-off between the study's theoretical goals and its practical budget constraints.
A research methods instructor asks students to apply their understanding of survey sample size principles to concrete research situations. Match each scenario to the principle of survey sample size determination it best illustrates.
A researcher plans a large-scale health survey and determines through a power analysis that 1,000 participants are needed to reach her desired level of statistical confidence. After reviewing her grant award, she discovers she can only afford 400 participants. By breaking down what is preventing her from achieving her ideal sample size, a careful reviewer would conclude that the binding determinant in this scenario is the study's _____.
A research methods instructor asks students to critically evaluate whether a researcher made well-justified decisions when determining her survey sample size. Arrange the following evaluative steps in the order that would allow a reviewer to reach the most defensible judgment about the appropriateness of the researcher's chosen sample size.
Explain the two primary factors that researchers must balance when determining the optimal sample size for a survey, and identify the tool they frequently use to balance these considerations.
Explain the theoretical and practical trade-offs Dr. Chen faces regarding her survey's sample size, and describe how a power analysis can help her resolve this dilemma.
A developmental psychologist wants to conduct a survey on parenting styles but has a limited budget of dollars. She wants to ensure her sample size is large enough to achieve a high level of statistical confidence but is concerned about recruitment costs. Apply the concepts of survey sample size determination to recommend how she should proceed to find the optimal sample size.