scopes chaps 5-9 vocab

Cluster sample

Cluster sample

A probability sample that is used when no list of elements exists. The sampling frame initially consists of clusters of elements.

Convenience sample

A nonprobability sample in which the selection of elements is determined by the researcher's convenience.

Disproportionate sample

A stratified sample in which elements sharing a characteristic are underrepresented or overrepresented in the sample.

Element

A particular case or entity about which information is collected; the unit of analysis.

Estimator

A statistic based on sample observations that is used to estimate the numerical value of an unknown population parameter.

Expected value

The mean or average value of a sample statistic based on repeated samples from a population.

Nonprobability sample

A sample for which each element in the total population has an unknown probability of being selected.

Population

All the cases or observations covered by a hypothesis; all the units of analysis to which a hypothesis applies.

Population parameter

A characteristic or an attribute in a population (not a sample) that can be quantified.

Probability sample

A sample for which each element in the total population has a known probability of being selected.

Proportionate sample

A probability sample that draws elements from a stratified population at a rate proportional to the size of the samples.

Purposive sample

A nonprobability sample in which a researcher uses discretion in selecting elements for observation.

Quota sample

A nonprobability sample in which elements are sampled in proportion to their representation in the population.

Sample

A subset of observations or cases drawn from a specified population.

Sample bias

The bias that occurs whenever some elements of a population are systematically excluded from a sample. It is usually due to an incomplete sampling frame or a nonprobability method of selecting elements.

Sample statistic

The estimator of a population characteristic or attribute that is calculated from sample data.

Sampling distribution

A theoretical (nonobserved) distribution of sample statistics calculated on samples of size N that, if known, permits the calculation of confidence intervals and the test of statistical hypotheses.

Sampling error

The difference between a sample estimate and a corresponding population parameter that arises because only a portion of a population is observed.

Sampling fraction

The proportion of the population included in a sample.

Sampling frame

The population from which a sample is drawn. Ideally, it is the same as the total population of interest to a study.

Sampling interval

The number of elements in a sampling frame divided by the desired sample size.

Sampling unit

The entity listed in a sampling frame. It may be the same as an element, or it may be a group or cluster of elements.

Simple random sample

A probability sample in which each element has an equal chance of being selected.

Snowball sample

A nonprobability sample in which potential respondents are identified by respondents already participating in the sample.

Statistical inference

The mathematical theory and techniques for making conjectures about the unknown characteristics (parameters) of populations based on samples.

Stratified sample

A probability sample in which elements sharing one or more characteristics are grouped and elements are selected from each group in proportion to the group's representation in the total population.

Stratum

A subgroup of a population that shares one or more characteristics.

Systematic sample

A probability sample in which elements are selected from a list at predetermined intervals.

Causes-of-effects approach

An approach to causal questions that starts with an outcome and works backward to the causes. Emphasis is on identifying causes of outcomes.

Classical randomized experiment

An experiment with the random assignment of subjects to experimental and control groups with a pretest and post test for both groups.

Control group

A group of subjects that does not receive the experimental treatment or test stimulus.

Correlation

A statement that the values or states of one thing systematically vary with the values or states of another; an association between two variables.

Demand characteristics

Aspects of the research situation that cause participants to guess the purpose or rationale of the study and adjust their behavior or opinions accordingly.

Effects-of-causes approach

An approach to causal questions that starts with a potential cause and works forward to measure its impact on the outcome. Emphasis is on measuring the size of the effect that a cause has on an outcome.

Experiment

Research using a research design in which the researcher controls exposure to the test factor or independent variable, the assignment of subjects to groups, and the measurement of responses.

Experimental effect

Effect, usually measured numerically, of the experimental variable on the dependent variable.

Experimental group

A group of subjects that receives the experimental treatment or test stimulus.

Experimental mortality

A differential loss of subjects from experimental and control groups that affects the equivalency of groups; threat to internal validity.

External validity

The ability to generalize from one set of research findings to other situations.

Internal validity

The ability to show that manipulation or variation of the independent variable actually causes the dependent variable to change.

Large N studies

Quantitative research designs in which the research examines many cases of a phenomenon.

Pretest

Measurement of variables prior to the administration of the experimental treatment or manipulation of the independent variable.

Randomization

The random assignment of subjects to experimental and control groups.

Research design

A plan specifying how the researcher intends to fulfill the goals of the study; a logical plan for testing hypotheses.

Selection bias

Bias due to the assignment of subjects to experimental and control groups according to some criterion and not randomly; threat to internal validity.

Small N studies

Research designs in which the research examines one or a few cases of a phenomenon in considerable detail.

Stimulus or test factor

The independent variable introduced and controlled by an investigator in order to assess its effects on a response or dependent variable.

Case study design

A comprehensive and in-depth qualitative study of a single case or several cases. A nonexperimental design in which the investigator has little control over events.

Causally heterogeneous population

A population in which a given cause might have many different effects across different cases or the same cause is linked to the same outcome through different causal mechanisms.

Causally homogeneous population

A population in which a given cause can be expected to have the same causal relationship with the outcome across cases in the population.

Counterfactual understanding of causation

The logical argument that support for the claim that A causes B is demonstrated by a case in which A is absent and B does not occur.

Deviant case

A case that exhibits all of the factors thought to lead to a particular outcome, but in which the outcome does not occur.

Hypothesis-generating case study

A type of case study that attempts to develop from one or more cases some general theoretical propositions that can be tested in future research.

Hypothesis-testing case study

A type of case study that attempts to test hypothesized empirical relationships.

Idiographic case study

A type of case study that attempts to describe, explain, or interpret a singular historical episode with no intention of generalizing beyond the case.

Least likely case

A case in which it is expected that a theory is least likely to apply.

Mechanistic understanding of causation

An approach to demonstrating or understanding causation by focusing on the mechanism by which a cause leads to an outcome.

Method of agreement

A comparative strategy wherein the researcher selects cases that share the same outcome and identifies those conditions or causal factors that the cases also have in common.

Method of difference

A comparative strategy wherein the researcher selects cases in which the outcomes differ, compares the cases looking for the single factor that the cases do not have in common, and concludes that this factor is causal.

Most likely case

A case in which theory predicts an outcome is most likely to occur.

Necessary cause

A condition that must be present in order for the outcome to occur.

Plausibility probes

A case study that is not expected to provide a definitive test of the connection between a cause and an outcome, but is expected to contribute to conducting such a test in the future.

Process tracing

A case study in which a causal mechanism is traced from causal condition to final outcome.

Sufficient cause

A condition with which the outcome is always found.

Accretion measures

Measures of phenomena through indirect observation of the accumulation of materials.

Covert observation

Observation in which the observer's presence or purpose is kept secret from those being observed.

Direct observation

Actual observation of behavior.

Document analysis

The use of audio, visual, or written materials as a source of data.

Elite interviewing

Interviewing individuals who possess specialized knowledge about a political phenomenon.

Episodic records

Materials that are not part of a systematic and ongoing record-keeping effort.

Erosion measures

Measures of phenomena through indirect observation of selective wear of some material.

Ethnography

A type of field study in which the researcher is deeply immersed in the place and lives of the people being studied.

Field studies

Open-ended and wide-ranging (rather than structured) observation in a natural setting.

Firsthand observation

Method of data collection in which the researcher personally observes political behavior or some physical trace of it.

Indirect observation

Observation of physical traces of behavior.

Informed consent

Procedures that inform potential research subjects about the proposed research in which they are being asked to participate; the principle that researchers must obtain the freely given consent of human subjects before they participate in a research project.

Institutional review board

Panel to which researchers must submit descriptions of proposed research involving human subjects for the purpose of ethics review.

Interview data

Data that are collected from responses to questions posed by the researcher to a respondent.

Nonparticipant observation

Observation of activities, behaviors, or events in which the researcher does not participate.

Overt observation

Observation in which those being observed are informed of the observer's presence and purpose.

Participant observation

Observation in which the observer becomes a regular participant in the activities of those being observed.

Primary data

Data recorded and used by the researcher who is making the observations.

Reactivity

Effect of data collection or measurement on the phenomenon being measured.

Running record

Materials or data that are collected across time.

Secondary data

Data used by a researcher that were not personally collected by that researcher.

Structured observation

Systematic observation and recording of the incidence of specific behaviors.

Unstructured observation

Observation in which all behavior and activities are recorded.

Written record

Documents, reports, statistics, manuscripts, photographs, audio recordings, and other recorded materials available and useful for empirical research.

Age effects

Effects associated with the process of becoming older.

Cohort

A group of people who all experience a significant event in roughly the same time frame.

Cross-sectional design

A research design in which measurements of independent and dependent variables are taken at the same time; naturally occurring differences in the independent variable are used to create quasi-experimental and quasi-control groups; and extraneous factors are controlled for by statistical means.

Field experiment

Experimental designs applied in a natural setting.

Intervention analysis

A nonexperimental time-series design in which measurements of a dependent variable are taken both before and after the "introduction" of an independent variable.

Multiple-group design

Experimental design with more than one control and experimental group.

Natural experiment

A study in which there is random assignment or "as-if" random assignment of units to experimental and control groups but the researcher does not control the randomization process or the manipulation of the treatment factor.

Observational study

A nonexperimental research design in which the researcher simply observes differences in the dependent variable for naturally occurring treatment and control groups.

Period effect

An indicator or measure of history effect on a dependent variable during a specified time.

Posttest design

A research design in which the dependent variable is measured after, but not before, manipulation of the independent variable.

Quasi-experimental design

A research design that includes treatment and control groups to which individuals are not assigned randomly.

Repeated-measurement design

A plan that calls for making more than one measure or observation on a dependent variable at different times over the course of the study.