AP Statistics Unit 1 Vocabulary Study Guide

A comprehensive vocabulary flashcard set covering sampling methods, bias types, experimental designs, and core concepts for AP Statistics Unit 1.

Population

The entire group you want information about.

Sample

The smaller group actually studied from a population.

Simple Random Sample (SRS)

A sampling method in which every possible group of the same size has an equal chance of being selected.

Stratified Random Sample

A sampling method where the population is divided into groups (strata) based on an important characteristic, and a random sample is taken from every group.

Cluster Sample

A sampling method where the population is divided into groups (clusters), some clusters are randomly selected, and everyone in those selected clusters is surveyed.

Systematic Sample

A sampling method where individuals are chosen using a fixed pattern or interval, such as selecting every $k\text{th}$ person.

Convenience Sample

A sampling method where researchers choose people who are easy to reach, which usually creates bias.

Bias

A condition occurring when a sampling method systematically favors certain outcomes or certain members of the population.

Voluntary Response Bias

A type of bias that occurs when people choose whether to respond, making individuals with strong opinions more likely to participate.

Undercoverage

A sampling issue where some members of the population are less likely or unable to be included in the sample.

Nonresponse Bias

A type of bias that occurs when individuals are selected for a sample but do not respond, creating bias if non-responders differ from responders.

Response Bias

A type of bias that occurs when participants give inaccurate answers due to factors such as embarrassing questions, interviewer pressure, or poorly worded questions.

Observational Study

A study in which researchers observe outcomes without assigning treatments to subjects, which can show association but cannot establish cause and effect.

Experiment

A study in which researchers impose or assign treatments to subjects, which can support cause-and-effect conclusions if properly designed.

Explanatory Variable

The variable that may explain or cause changes in another variable.

Response Variable

The variable that measures the outcome of a study.

Experimental Units

The individuals or items that receive the treatments in an experiment.

Treatment

The specific condition given to an experimental unit in an experiment.

Random Assignment

The process of randomly placing experimental units into treatment groups, which helps establish cause and effect by creating roughly equivalent groups.

Random Sampling

The process of selecting individuals randomly from a population, which creates a representative sample and allows for generalizing results to the population.

Control Group

A comparison group in an experiment that receives no treatment, a placebo, or the standard treatment.

Placebo

A fake treatment that looks and feels like the active treatment but does not contain the active ingredient.

Placebo Effect

A response that occurs because a participant believes they are receiving a treatment, rather than because of the treatment itself.

Single-Blind

A study design where one group involved in the study does not know which treatment was received.

Double-Blind

A study design where neither the subjects nor the people interacting with or evaluating them know who received which treatment.

Blocking

The practice of dividing experimental units into groups based on a characteristic that could affect the response, then randomly assigning treatments within each block.

Matched-Pairs Design

A special type of blocking design where either pairs of very similar subjects are assigned different treatments, or each subject receives both treatments.

Completely Randomized Design

An experimental design in which every experimental unit is randomly assigned directly to a treatment group without using blocks.

Confounding

A scenario where the effects of two variables cannot be separated because a confounding variable is related to the explanatory variable and affects the response variable.

Principles of Experimental Design

The three fundamental rules of experimental design: control (keeping other conditions similar), randomization (randomly assigning treatments), and replication (using enough experimental units).

Census

A study that collects data from every single individual in the entire population.