Statistics Chapter 1

Statistics

The science concerned with the collection, interpretation, and presentation of data.

Data

A collection of observations or measurements.

Population

An entire collection of data.

Sample

A subcollection of all data.

Voluntary response sample

A non-random sampling method where respondents volunteer to answer.

Parameter

A measurement describing a population.

Statistic

A measurement describing a sample.

Quantitative data

Data that consists of counts and measurements.

Categorical data

Data concerning non-measuring names and labels, also called qualitative or attribute data.

Discrete numerical data

Data that can be counted reliably.

Continuous data

Data that technically can’t be counted due to infinitely many values in its range.

Nominal level of measurement

Data that can’t be ordered or arranged and should not be used in direct calculations.

Ordinal level of measurement

Data that can be arranged, but subtracting them would be meaningless.

Interval level of measurement

Data that can be arranged and subtracted, but lacks a “true” zero.

Ratio level of measurement

Data that can be arranged, subtracted, and interpreted with a “true zero.”

Experiment

A study that observes the effects of a treatment on subjects.

Observational study

A study that observes people as-is without trying to change them.

Random sample

A sample where all of a population had the same chance of being selected.

Simple random sample

A sample where there is an equal chance of selecting another sample of the same size.

Systematic sample

A sample that takes a pattern of subjects, such as every 5th.

Convenience sample

A sample that takes whatever data is simple to get.

Cluster sample

A sample that divides a population into clumps and then selects samples from those partitions.

Stratified sample

A sample that divides a population into strata and then randomly samples from those strata.