AP Stats Unit 4 terms

Simple Random Sample (SRS)

A sampling method where every member of the population has an equal chance of being selected.

Convenience Sample

A sample taken from a group that is easy to reach or contact, which may not represent the entire population.

Voluntary Response Sample

A sample that relies on individuals volunteering to participate, often leading to bias due to self-selection.

Stratified Random Sample

A sampling method where the population is divided into subgroups and a simple random sample is taken from each subgroup.

Cluster Sample

The population is divided into clusters, and entire clusters are randomly selected for the sample.

Systematic Random Sample

A sample where you select every 'kth' individual from a list of the population.

Undercoverage

A sampling error where some groups in the population are left out or underrepresented in the sample.

Non-Response

Occurs when individuals chosen for the sample do not respond, which can lead to bias.

Response Bias

When the phrasing of a question or the asking environment influences responses, leading to skewed data.

Confounding Variables

Extra variables that can affect the relationship between independent and dependent variables.

Observational Study

Observes and measures variables without influencing them, revealing associations but not proving causation.

Experiment

A study that actively applies treatments to experimental units to measure effects and establish causation.

Experimental Units

The individuals or objects receiving the treatment in an experiment.

Treatments

The different conditions applied to the experimental units in an experiment.

Components of an Experiment

Key elements including experimental units, treatments, control groups, random assignment, and response measurements.

Random Assignment

The random assignment of experimental units to treatments to reduce bias and ensure group similarity.

Placebo Effect

A psychological phenomenon where participants experience improvements due to believing they are receiving treatment.

Randomized Block Design

An experimental design dividing subjects into blocks based on characteristics, then randomly assigning treatments within blocks.

Matched Pairs Design

An experimental design where subjects are paired based on similarities and assigned different treatments.

Simulation

A method modeling real-life situations to study different possible outcomes, often using random numbers.

Statistical Significance

When an observed effect is so large or consistent that it is unlikely to have occurred by chance.

Purpose of Using a Random Sample

To ensure every individual in the population has an equal chance of being chosen for a more representative sample.

Purpose of Using Random Assignment

To ensure differences in treatment outcomes can be attributed to the treatments, helping establish causation.