# Ratio scale

The **ratio **scale , also known as the **rational **scale , **ratio scale** or **proportional **scale , is the highest level in statistics . It is a metric scale, but unlike the interval scale, there is an absolute zero point (e.g. blood pressure, temperature in Kelvin, age). Only at this scale level are multiplication and division meaningful and permitted. Relationships between characteristic values can therefore be created (e.g. for a number and characteristic values ).

## description

Characteristic values are entered on a **ratio / rational** scale for which the following applies:

- Characteristic values are shown as numbers
- for the numerical values there is a natural zero point and
- the unit of measurement is defined arbitrarily (see absolute scale )

In the case of ratio scales, the numbers correspond to the strength of the characteristic values. Permissible statements are e.g. B. "Mr. X has grown by 15%".

## Examples

The table below contains examples of ratio-scaled features for temperature, time, weight, price, speed and length measurements.

feature | Zero point |
---|---|

Temperature in Kelvin | Absolute zero |

Duration | no duration |

Dimensions | no mass |

price | free |

speed | no speed, standstill |

distance | no distance |

## Possible operations

The following operations can be performed with features that measure on a ratio scale:

- Compare on identity
- Size comparisons
- Additions, subtractions
- Multiplication with a number (the result is a characteristic value), division of two characteristic values (the result is a number)

## Allowed transformations

Multiplicative transformations of the type with are permitted .