AP STATS 4.2 Part 1

Stratified Random Sample

Sample consisting of separate simple random samples drawn from group of similar individuals.

Strata

Groups of similar individuals in a population.

Placebo

“fake” treatment that is sometimes used in an experiment to test validity of a treatment.

Block

Group of experimental unites that are similar in some way that may affect the response to treatment

Control

Effort to minimize variability in the way experimental units are obtained and treated

Random Assignment

Rule used to assign experimental units to treatments.

Inference

Process of drawing conclusions about the population based on a sample

Clusters

Small groups of individuals who mirror the population.

Observational Study

Type of study that cannot be used to establish cause-effect relationships.

Undercoverage

When an individual chosen for the sample can’t be contacted or refuses to participates.

Replication

Practice of using enough subjects in an experiment to reduce chance variation.

Significant

An observed affect that is too large to have occurred by chance alone

Bias

This happens when study systematically factors certain outcomes.

Convenience Sample

A sample in which we choose individuals who are easiest to reach

Experimental Study

Study in which a treatment is imposed in order to observe a response.

Voluntary Response Sample

A sample consisting of people who choose themselves by responding to general appeal. Choose to participate and have strong opinions.

Population

Entire group of individuals about which we want information

Double Blind Experiment

Experimental study in which neither the subject nor those measuring response know which treatment subjects recieve.

Simple Random Sample

Sample consisting of individuals from the population, each of which has an equally likely chance of being included/choosen.

Subjects

Term for when units are human.

Sample

The part of a population from which we actually collect data from.

Cluster Sample

Sample consisting of simple random sample of small groups/clusters from a population.

Levels

Another name for treatments.

Experimental Units

Individuals on which an experiment is done.