AP Stats 4.1 Vocab

Population

Population

the entire group of individuals we want information about

Sample

a subject of individuals whith-in the population from which we actually collect data.

Census

collects data from every individual in the population

Cluster

A group of individuals in the population that are located near eachother

convenience sampling

choosing individuals from the population who are easiest to reach. = unrepresentative data

Bias

underestimate or overestimate the value you want to know

voluntary response sampling

consists of people who choose themselves by responding to a general appeal

random sampling

using a chance process to determine which members of a population are included in the sample.

simple random sample

size n is chosen in such a way that every group of n individuals in the population has an equal chance to be selected as the sample

strata

subject of the population which is being sampled.

stratified random sampling

Population divided into subgroups (strata) and random samples taken from each strata.

cluster random sampling

dividing the total population into groups (or clusters), then using simple random sampling to select which clusters participate; all observations in a selected cluster are included in the sample

Under coverage

Occurs when some members of the population cannot be chosen for a sample.- can't be contacted

nonresponse

Occurs when an individual chosen for a sample can’t be contacted or refuses to participate

Response bias

Systematic pattern of incorrect responses in an sample survey.- usually caused by weird worded questions by interviewer

Extrapolation

Use of regression model for prediction outside of the interval of x values used to obtain the model. The further out you go, the less reliable the perditions are.

Heterogeneous

When individuals in a group differ. Ideal for clusters

Homogeneous

When individuals are quite similar. Ideal for Strata