DATASCI: Chapter 1

population

the set of all subjects of intrest

Sample

the subset of the population of interest on which you collect data

Census

including everyone and sampling the entire population

Non-response

occurs when an individual chosen for the sample can't be contacted or refuses to participate

Voluntary response

Occurs when the sample consist of people who volunteer to respond because they have strong opinions on the issue

Convenience sample

Individuals who are easily accessible are more likely to be included in the sample

Continuous variable

A variable (such as age, test score, or height) that can take on a wide or infinite number of values.

Discrete variable

a quantitative variable that has either a finite number of possible values or a countable number of possible values

Regular categorial variable

a qualitative variable that has defined categories

Ordinal variable

Categorical variable with a defined order.

Associated variables

two variables that show some connection with one another

Independent variable

two variabes that are not assocated or have no evident connection betweent the two

Simple Random Sample

A sample of size n selected from the population in such a way that each possible sample of size n has an equal chance of being selected.

Stratified sample

a sample drawn in such a way that known subgroups within a population are represented in proportion to their numbers in the general population

Strata

made up of similiar observations

Cluster sample

a sampling design in which entire groups are chosen at random

Clusters

small groups that are usually not made up of homogenous observations

Multistage sample

A sample resulting from multiple applications of cluster, stratified, and/or simple random sampling.