Chapter 4: Designing Studies — Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on Sampling, Surveys, Inference, and Experiments (Chapter 4).

Population

The entire group of individuals about which we want information.

Census

A survey of every individual in the population.

Sample

A subset of the population from which information is collected to draw conclusions about the population.

Parameter

A numerical description of a population characteristic.

Statistic

A numerical value computed from a sample used to estimate a population parameter.

Randomization

Using chance to select or assign subjects to reduce bias in sampling or experiments.

Simple Random Sample (SRS)

A sample of size n in which every set of n individuals has the same chance of being chosen; draws are independent.

Label

A unique identifier assigned to each member of the population for sampling.

Sampling Frame

The list of individuals from which a sample is drawn.

Undercoverage

When some groups in the population are left out of the sampling process.

Nonresponse

When a selected individual cannot be contacted or refuses to participate.

Response Bias

A systematic pattern of incorrect responses in a survey.

Voluntary Response

Bias that occurs when the sample consists of individuals who choose to respond.

Convenience Sample

A sample that is easy to reach; often biased.

Stratified Sample

Divide the population into strata (groups) and take an SRS from each stratum.

Cluster Sample

Divide the population into clusters, then randomly select clusters and survey members within those clusters.

Multistage Sample

Sampling conducted in multiple stages, such as selecting groups within groups (e.g., state → county → city → neighborhood).

Inference

Drawing conclusions about a population from a sample.

Observational Study

Observing individuals and measuring variables without applying a treatment.

Experiment

Deliberately imposing a treatment on individuals and measuring the responses.

Treatment

A specific condition applied to individuals in an experiment.

Experimental Unit

The smallest unit to which treatments are applied.

Subject

When experimental units are humans.

Factor

An explanatory variable in an experiment; may have several levels.

Level

A specific value that a factor can take.

Explanatory Variable

Another term for the independent variable; explains or predicts changes in the response.

Response Variable

The outcome measured in the study.

Lurking Variable

A variable not among the explanatory or response variables that may influence the response.

Confounding Variable

A lurking variable that is associated with both the explanatory and the response variables, causing confounding.

Randomized Block Design

Random assignment to treatments is performed separately within blocks; blocks are groups known before the experiment.

Block

A group of experimental units that is known before the experiment begins.

Stratified Random Sample

A sampling method where the population is divided into strata and an SRS is drawn from each stratum.

Statistically Significant

An observed effect so large that it would rarely occur by chance.

Scope of Inference

The range of populations or cause-and-effect relationships to which conclusions apply, depending on whether the study used random selection or random assignment.