Research and Methods Exam 2

Population

The entire set of elements in which a researcher is interested.

Sample

A subset of elements selected from a larger population.

Element

An individual member of a population whose characteristics are measured.

Sampling frame

A list of population elements from which a sample is selected.

Sampling unit

The unit selected at a particular stage of sampling.

Primary sampling unit

The unit selected in the first stage of sampling, such as prisons in a study of inmates.

Secondary sampling unit

The unit selected at a later stage of sampling, such as individual inmates within selected prisons.

Sample generalizability

The ability to generalize findings from a sample to the population from which it was drawn.

Cross-population generalizability

The ability to generalize findings from one group, population, or setting to other groups, populations, or settings.

Representative sample

A sample that accurately reflects the important characteristics of the target population.

Unrepresentative sample

A sample in which important population characteristics are overrepresented or underrepresented.

Sampling error

The difference between a sample estimate and the true population value due to sampling variation.

Simple random sampling

A probability sampling method in which selection is based entirely on chance, giving population elements a known chance of selection.

Systematic random sampling

A probability sampling method in which a random starting point is chosen and every kth element is selected from a list.

Stratified random sampling

A probability sampling method in which the population is divided into predetermined strata and samples are selected randomly from each stratum.

Multistage cluster sampling

A probability sampling method involving multiple stages, beginning with randomly selected natural clusters and proceeding to smaller units within them.

Availability sampling

A nonprobability sampling method in which elements are selected based on convenience or accessibility.

Purposive sampling

A nonprobability sampling method in which elements are deliberately selected for a particular purpose or because of relevant characteristics; also called judgment sampling.

Snowball sampling

A nonprobability sampling method in which participants identify or recruit additional participants through successive referrals.

Unit of analysis

The person, group, organization, or other level of social life about which a research question draws conclusions.

Empirical association

A relationship in which variation in an independent variable is associated with variation in a dependent variable.

Time order

A criterion for causation requiring the independent variable to change before the dependent variable.

Nonspuriousness

A criterion for causation requiring a relationship between two variables not to be explained by a third variable.

Mechanism

A discernible process that explains how one variable causes a change in another.

Context

The broader set of interrelated circumstances in which an outcome occurs and is explained.

True experiment

A research design that uses experimental and comparison groups, random assignment, and assessment of changes in the dependent variable.

Experimental group

The group that receives the treatment or intervention being studied.

Control group

A comparison group that receives no treatment, a placebo, or a different treatment, depending on the study design.

Random assignment

The process of assigning subjects to experimental conditions by chance.

Change in the dependent variable

The difference in the measured outcome after the experimental condition, assessed to determine the treatment's effect.

Causality in true experiments

Causal relationships are assessed by controlling conditions and comparing outcomes across randomly assigned groups.

Nonexperimental design

A research design that observes variables without randomly assigning subjects to experimental conditions.

Cross-sectional design

A study in which data are collected at one point in time.

Longitudinal design

A study in which data are collected at two or more points in time.

Repeated cross-sectional design

A longitudinal design that collects data at multiple times from different samples of the same population.

Fixed-sample panel design

A longitudinal design that collects data from the same individuals at multiple times.

Panel attrition

The loss of participants from a panel study over time.

Cohort-based design

A longitudinal design that studies people who share a defining experience or characteristic during a particular period, such as birth year or graduation year.

Time order in nonexperimental research

Time order can be established with longitudinal data more readily than with cross-sectional data.

Nonspuriousness in nonexperimental research

Researchers assess whether a third variable could explain the observed relationship between variables.

Mechanism in nonexperimental research

Longitudinal evidence and theory can help identify the process linking variables.

Quasi-experimental design

A research design with a comparison group similar to the experimental group in important ways, but without random assignment to groups.

Nonequivalent control group design

A quasi-experimental design in which experimental and comparison groups are established before treatment without random assignment.

Causality in quasi-experiments

Researchers evaluate association, time order, and nonspuriousness while accounting for the absence of random assignment.

Internal validity

The extent to which an experiment supports a valid conclusion that the treatment caused the observed outcome.

Selection bias

A threat to internal validity caused by preexisting differences between experimental and comparison groups.

Endogenous change

A threat to internal validity when participants change over time for reasons independent of the treatment.

External events

Events occurring during a study, other than the treatment, that influence outcome scores.

Contamination

A threat to validity in which one group is influenced by knowledge of or interaction with the other group.

Treatment misidentification

A situation in which an outcome changes with the treatment, but the researcher incorrectly identifies the process responsible for that change.

Survey research

A research method that collects standardized information from respondents through questions.

Versatility of surveys

The ability of surveys to investigate many topics, populations, and variables.

Efficiency of surveys

The ability to collect information from many people with relatively limited time and resources.

Generalizability of surveys

The potential to apply findings to a broader population when sampling and response quality support it.

Questionnaire

The survey instrument containing questions completed by respondents themselves.

Interview schedule

The survey instrument containing questions asked by an interviewer in person or over the phone.

Respondent

A person who answers survey questions.

Response rate

The proportion of eligible or sampled people who complete a survey, based on the study's stated calculation method.

Maintain focus in questionnaire development

Ensure that every question supports a clearly defined research objective and target population.

Irrelevant survey questions

Questions that do not contribute to the study's objectives and should generally be excluded.

Existing survey instrument

A previously developed set of questions designed to measure a concept or behavior.

Why use existing survey instruments?

Previously tested questions may provide established measures and improve consistency with earlier research.

Survey translation

The process of adapting a questionnaire to another language while preserving the meaning of its concepts and questions.

Cultural equivalence in surveys

Ensuring that questions and concepts have comparable meanings across languages and cultures.

Open-ended question

A survey question that does not provide explicit response choices and allows respondents to answer in their own words.

Closed-ended question

A survey question that provides explicit response options for respondents to choose from.

Clear survey question writing

Use correct grammar, simple and unambiguous wording, and concise phrasing.

Fixed-response question

A question that provides predetermined response choices, often making answers easier to compare and analyze.

Demographic questions

Questions about characteristics such as age, sex, race or ethnicity, income, and religion.

Placement of demographic questions

Demographic questions are often placed near the end of a questionnaire, although some surveys place them at the beginning.

Pretest

A trial administration of survey questions to identify confusing wording, response problems, or other issues before the main survey.

Questionnaire organization

Grouping and ordering questions into coherent sections that support the research objectives.

Descriptive questionnaire title

A title that communicates the overall topic of the survey.

Contextual message

An introductory message explaining the survey's purpose and relevant information to respondents.

Mailed survey

A survey distributed through postal mail, sometimes useful for reaching geographically dispersed populations with limited interviewing resources.

Group-administered survey

A survey completed individually by respondents gathered together in one setting.

Phone survey

A survey administered by telephone, allowing interviewers to ask questions and follow up with respondents.

In-person survey

A survey administered face-to-face, useful for lengthy or complex questionnaires.

Electronic survey

A survey completed digitally, such as through email or a website.

Independent variable

The variable hypothesized to influence or cause changes in another variable.

Dependent variable

The outcome variable whose variation researchers seek to explain.

Probability sampling

Sampling in which elements are selected using a random process and have known, nonzero selection probabilities.

Nonprobability sampling

Sampling in which elements are selected without random selection probabilities being known.

Sampling interval

The fixed number of positions between selected elements in systematic random sampling.

Natural cluster

A naturally occurring group, such as a school, prison, or geographic area, used as a sampling unit.

Why use random assignment?

To make experimental groups comparable on average and reduce systematic preexisting differences.

Why use a control group?

To provide a comparison that helps researchers estimate what would have happened without the treatment or under another condition.

Why assess change in the dependent variable?

To determine whether the outcome differs after the experimental condition and between comparison groups.

Internal versus external validity

Internal validity concerns whether the treatment caused the outcome; external validity concerns whether findings generalize beyond the study.

Cross-sectional limitation for causality

Because variables are measured at one time, cross-sectional studies usually cannot establish which variable came first.

Longitudinal advantage for causality

Measurements at multiple times can help establish temporal order and examine change.

Availability versus purposive sampling

Availability sampling selects accessible participants; purposive sampling selects participants for specific relevant characteristics or purposes.

Stratified versus cluster sampling

Stratified sampling randomly samples from each defined subgroup; cluster sampling selects groups and may then sample elements within them.

Repeated cross-sectional versus panel design

Repeated cross-sectional studies use different samples from the same population over time; panel studies follow the same individuals.

True experiment versus quasi-experiment

A true experiment uses random assignment; a quasi-experiment does not.

Treatment effect

The change in an outcome attributable to a treatment, as distinguished from changes that would have occurred without it.

Sampling frame coverage error

Error that occurs when the sampling frame excludes eligible population members or includes ineligible ones.

Response bias

Systematic inaccuracy in survey answers caused by factors such as question wording, social desirability, or respondents' reporting behavior.

Nonresponse bias

Bias that occurs when people who do not respond differ meaningfully from those who do respond.

Social desirability bias

A response bias in which respondents give answers they believe will be viewed favorably by others.