Stats Unit 1 Notes

Individuals

People, animals, objects, or groups of items of one kind studied in statistics.

Variables

Attributes or characteristics of individuals that can vary between them.

Constant

A special case of a variable that does not change, e.g., the number of eyes in a cat.

Data

Values of a variable measured or assessed on individuals, with singular being 'datum'.

Population

The set of all individuals of a given kind about whom information is desired.

Parameters

Characteristics of a population, usually estimated from sample statistics.

Sample

A subset of a population that is actually studied to make inferences about the population.

Descriptive statistics

Branch of statistics that describes a population by calculating parameters from population data.

Inferential statistics

Branch of statistics that estimates or predicts population parameters using sample statistics.

Explanatory variable

The factor thought to be causing changes in the outcome.

Response variable

The outcome that is being measured or predicted in a study.

Lurking variable

A variable not included in the analysis that affects both explanatory and response variables.

Confounding variable

A lurking variable that is related to both the independent and dependent variables.

Numeric variable

A variable that represents data which can be measured on a numeric scale.

Categorical variable

A variable that represents data grouped into categories.

Distribution

Shows how values of a variable are spread or arranged.

Point estimation

Estimating a parameter from sample data.

Confidence Interval (C.I.)

A range within which the true population parameter is likely to fall.

Random Sampling

Every individual has an equal chance of being selected from the population.

Stratified Sampling

Population is divided into subgroups, and random samples are taken from each subgroup.

Cluster Sampling

Entire groups or clusters are selected at random, and all individuals within those clusters are surveyed.

Systematic Sampling

Every k-th individual is selected from a population list.

Convenience Sampling

Samples are chosen based on what is easiest or most convenient.

Voluntary Response Sampling

Individuals choose to participate, often leading to biased results.