AP Statistics Unit 2 - Collecting Data Study Guide

Flashcards covering sampling methods, biases, experimental designs, and statistical terminology from the Unit 2 AP Statistics exam study guide.

Simple Random Sample

A sampling method where every sample of a given size has an equal chance of being selected, often implemented using names in a hat, popsicle sticks, or a random number generator.

Voluntary Sample

A sample created when individuals choose themselves to take part in a study or survey.

Convenience Sample

A sampling method where data is collected from individuals who are easily attainable.

Stratified Random Sample

A sampling method where the population is broken into distinct groups (strata) that share similar characteristics before random samples are taken from each group.

Cluster Random Sample

A sampling method where a large population is divided into naturally occurring groups or clusters, and entire clusters are randomly selected to be studied.

Undercoverage Bias

A sampling bias that occurs when certain members of the population are less likely to be chosen or included in the sample (e.g., calling landlines only).

Non-Response Bias

A bias that occurs when selected individuals cannot be reached or decline to participate in a study (e.g., ignoring phone calls or emails).

Response Bias

A systemic pattern of inaccurate answers or problems arising during the data gathering process.

Confirmation Bias

The tendency to favor or seek out evidence that supports pre-existing beliefs.

Selection Bias

Bias introduced when selecting individuals for a study in a way that creates a non-representative sample.

Halo Effect

A cognitive bias where a single overall impression or positive trait about an individual influences judgment of their other traits.

Observer Bias

A bias occurring when researchers allow their own personal assumptions or expectations to influence how they view or record data.

Explanatory Variable

A variable used to explain, predict, or affect changes in a response variable.

Response Variable

The main outcome or dependent variable measured in a study.

Experimental Unit

The individual subject or specific entity receiving treatments in an experiment.

Treatment

A specific condition or method applied to experimental units to observe its effect.

Random Sample Purpose

Allows for the generalization of study results to a larger population.

Random Assignment Purpose

Allows for claims of cause-and-effect relationships (causation) between variables.

Statistical Significance

An observed result or difference so large that it cannot be easily explained by random variation alone.

Completely Randomized Design

An experimental design in which all experimental units are assigned to treatment groups entirely by chance.

Randomized Block Design

An experimental design where subjects are first grouped into blocks based on similar characteristics, followed by random assignment to treatments within each block.

Matched Pairs Design

A special form of randomized block design where blocks consist of pairs of similar experimental units or where each subject receives both treatments as their own control.