AP Stats Chpt 4 Quiz Vocab

Lurking Variables

hidden factors not included that affect the relationship between the actual variables being analyed

Sampling Variability

Variation that can be accounted for by a margin or error

Convenience Sample

Choosing a sample based on availability, bad sample method (not representative)

Voluntary Response Sample

Group of individuals that choose to respond to a survey, bad sample method (allows for self-report bias)

Simple Random Sample (SRS)

Each individual of a population has an equal chance of being selected

Probability Sample/Systematic Sample

Sample chosen from a sequential listing of the population of interest, ex: every 3rd person

Stratified Random Sample

SRS from predetermined subgroups with a similar characteristic, a group → small groups, ex: everyone with red hair

Cluster Sample

Group sampling when population variability is expected within each of the groups, ex: clustering one side of a stadium

Observe and Record

Observe + record existing condition without influencing the subjects being studied (ex: observational study)

Impose and Measure

Subject individuals to a treatment while observing + recording responses, there is a direct attempt to control potential lurking variables, best way to show causation (ex: experiment)

Inference

The process of using data from a sample to make conclusions, predictions, or decisions about a population

Sampling Errors

Can be selection bias or undercoverage

Undercoverage

When a population is not being represented at all in a population/sample

Non-Sampling Error

Measurement or response bias or no response bias

Response bias

Untruthful answers

No Response Bias

Selected participant doesn’t respond

Experiment

Planned intervention designed to observe a response of an individual to a treatment

Treatment

Any combination of imposed, measurable factors

Factors

Explanatory variables E

Extraneous Factors

Factors that are not of interest but affect responses, lurking variables

Design

Plan for conducting an experiment

Experimental Units

Individuals being observed

Placebo

Identical to treatment with no active ingredient, placebo effect

Comparative Experiment

Treatment vs. control group for comparison, should be all experiments

Control Group

Made to attempt to eliminate extraneous factors

Randomization

Use of chance assignments to ensure that experiment does not favor one condition (usually the treatment)

Replication

Creating an adequate number of observations to reduce chance variations, repeated trails, sufficient number of consistent results, large enough sample

Statistical Significance

Responses so “large”/”likely” that they would rarely have occurred by chance

Randomized Assignment

Chance assignments of units to treatments/treatments to trials

Block Design

Restricted randomization to blocks with similar characteristics with the intent to control extraneous factors

Matched Pairs

Impose 2+ treatments on a single unit, the unit by itself is a control

Double Blind

Neither the researcher or the participant knows the treatment assignment