When a measurement refers to the whole population, it is called a *parameter*. When a measure refers to the sample, it is called a *statistic*. Statistics are thus estimates of the parameter.

## What is the nominal measurement level?

The simplest (lowest) measurement level is the nominal scale. For nominal variables, numbers only refer to categories. Measurement on the nominal scale categorize and label observations. The number 1 for example can be used for ‘men’ and the number 2 can be used for ‘women

...## What is the ordinal measurement level?

An ordinal variable comprises a set of categories with an ordering. For example, you can order the participants of a singing competition of worst to best on the basis of the applause they received. However, we can not determine perfectly how much more applause one or the

...## What is the interval measurement level?

An interval variable is a variable with a real number. Equal differences between number on this scale reflect equal differences in strength. However, with interval variables, there is no defined zero point. For example, you can not say a person has zero height. Because there

...## What is the ratio measurement level?

A ratio variable is a variable with a real number. Equal differences between number on this scale reflect equal differences in strength. Here, we do speak of a zero-level. Because of this, we are able to add, subtract, multiply and divide observations. Examples of ratio

...## Introduction to Statistics

Explanations, glossary and practice questions with fundamental concepts and tips, explanations and examples per topic when encountering, understanding and applying statistics

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