Vocab for Gathering Data (AP Stats Unit 1)

Random

When each outcome or selection is made without any predictable pattern or bias, ensuring that every possible outcome has an equal chance of occurring.

Components

What random numbers represent in a simulation, and is the aspect that is repeated and combined to form a trial based on a real-life situation

Population

the entire group of individuals or instances about whom we hope to learn.

Census

a study that attempts to collect data from every individual in the population.

Sample

a subset of the population that is used to represent the entire population

Sample Surveys

studies that ask questions of a sample drawn from a population in the hopes of learning something about that population.

Bias

tendency of a sampling method to systematically favor certain outcomes over others

Population Parameter

a value that describes a characteristic of the entire population.

Sample Statistic

Summary numbers of sampled data that describe a characteristic of a sample.

Simple Random Sample (SRS)

A sample where each individual in the population has an equal chance of being selected

Stratified Sample

involves dividing the population into homogenous groups (strata) and then taking a random sample from each group.

Homogeneous Groups

groups in which the members have similar characteristics.

Cluster Sample

The population is divided into heterogenous groups (clusters), then entire clusters are randomly selected

Heterogeneous Groups

groups in which the members have diverse characteristics.

Systematic Sample

Members are selected from a larger population according to a random starting point and a fixed interval (obtained by selecting every nth individual from a list of the population.)

Multistage Sample

involves using multiple sampling methods in stages to select a sample.

Response Bias

occurs when the responses given by participants are not accurate or truthful.

Non-Response Bias

occurs when individuals selected for the sample do not respond, and their non-responses are related to the study.

Observational Studies

involve observing and measuring variables without manipulating them.

Retrospective Observational Study

An observational study that looks back at past data to find correlations.

Prospective Observational Study

An observational study that follows individuals over time to observe future outcomes.

Experiments

Studies where a treatment is deliberately imposed on individuals to observe their responses (involves manipulating one or more variables to determine their effect on another variable)

Factor

an explanatory variable manipulated by the experimenter.

Participants/Subjects

The individuals taking part in a study, typically humans

Experimental Units

The objects (not human) to which treatments are applied in an experiment.

Levels of the Factor

The different values or categories of a factor in an experiment.

Treatment

A specific experimental condition applied to the subjects

Blocking

Grouping experimental units to reduce variability

Control Group

a group that does not receive the experimental treatment and is used for comparison.

Placebo

a fake treatment given to the control group to mimic the experience of the experimental group without giving the effect of the treatment (unless placebo effect occurs)

Single Blind

An experimental design where either the subjects or the experimenters do not know which treatment the subjects are receiving.

Double Blind

An experimental design where both the subjects and the experimenters do not know which treatment the subjects are receiving.

Matching

When subjects in a observational study are paired because they are similar in ways not under the study (reduces variation)

Confounding Variables

variables related to both the treatment and the outcome, making it difficult to determine the effect of the treatment.

Lurking Variables

variables that are not included in the study but could affect the results

Response Variable

the output or outcome of interest that is being modeled and analyzed

Simulation

method for collecting data that uses probability models to represent all possible outcomes of an experiment or process.

Trial

a single iteration or repetition of a simulation.