Unit 2: Collecting Data Flashcards

Vocabulary flashcards covering all terms listed under Unit 2 (Collecting Data), sections 2.1 through 2.8.

Convenience sample

A sampling method where individuals are selected based on easy accessibility or availability to the researcher.

Voluntary response sample

A sample composed of individuals who self-select or choose themselves to participate in a study or survey.

Simple random sample

A sampling method in which every group of $n$ individuals in the population has an equal chance of being selected for the sample.

Bias

Systematically favoring certain outcomes or overestimating or underestimating a population parameter.

Stratified random sample

A sampling method where the population is divided into homogeneous sub-groups (strata) and a simple random sample is drawn from each stratum.

Strata

Homogeneous sub-groups of a population divided based on specific shared characteristics prior to sampling.

Cluster random sample

A sampling method where the population is divided into heterogeneous groups (clusters), and a random sample of entire clusters is selected.

Systematic random sample

A sampling method where members of a population are selected according to a random starting point and a fixed, periodic interval.

Homogeneous

Describing groups whose members share similar or identical characteristics relevant to the study.

Heterogenous

Describing groups that contain a diverse mix of characteristics, representing the variability of the broader population.

Undercoverage

A type of sampling bias that occurs when some members of the population are less likely to be chosen or are completely left out of the sample frame.

Nonresponse

A bias that occurs when an individual chosen for the sample cannot be contacted or refuses to participate.

Response bias

A pattern of inaccurate responses resulting from question wording, interviewer behavior, or respondent misreporting.

Confounding variable

A variable related to both the explanatory and response variables, making it difficult to distinguish its effect from that of the explanatory variable.

Observational study

A study that measures individuals and observes outcomes without attempting to influence or impose treatments on the subjects.

Experiment

A study where treatments are deliberately imposed on experimental units to observe the resulting responses and establish cause-and-effect relationships.

Experimental units

The individual entities or subjects to which treatments are applied in an experiment.

Treatments

Specific conditions or combinations of factor levels applied to experimental units in an experiment.

Factor

An explanatory variable whose levels are manipulated by the experimenter in an experiment.

Extraneous variable

Any variable not under primary study that could potentially affect the outcome or response variable if not controlled.

Well-designed experiment

An experiment incorporating key principles such as comparison, random assignment, replication, and control to establish a valid cause-and-effect relationship.

Comparison

An experimental principle involving the use of two or more treatment groups to evaluate the effect of the treatment against a control or another treatment.

Random assignment

The process of using chance to assign experimental units to treatment groups, balancing the effects of unmeasured variables across groups.

Replication

The principle of applying treatments to multiple experimental units to reduce chance variation and assess the reliability of results.

Control

The experimental practice of keeping extraneous variables constant across all treatment groups to isolate the effect of the explanatory variable.

Placebo effect

A response occurring when subjects show improvement or change simply because they believe they are receiving a treatment.

Single-blind

An experimental design where either the subjects or the evaluators do not know which treatment a subject is receiving.

Double-blind

An experimental design where neither the subjects nor the individuals interacting with them to collect data know which treatment a subject is receiving.

Control group

A baseline group of experimental units receiving an inactive treatment, placebo, or standard treatment for comparison.

Completely randomized design

An experimental design where treatments are assigned entirely at random to all experimental units.

Randomized block design

An experimental design where subjects are first grouped into blocks of similar characteristics before treatments are randomly assigned within each block.

Block

A group of experimental units known before the experiment to be similar in ways expected to affect the response variable.

Matched-pairs design

A specialized randomized block design where subjects are paired based on similarities, or each subject receives both treatments in random order.

Statistically significant

An observed outcome or difference so large that it would rarely occur purely by random chance alone.