Ratio Scales of Measurement

Measurements expressed on a ratio scale can have an actual zero. Apart from this difference, ratio scales have the same properties as interval scales: the divisions between the points on the scale have the same distance between them and numbers on the scale are ranked according to size.

There are many examples of ratio scale measurements: length, weight, temperature on the kelvin scale, speed and counted values like numbers of people, exam marks - a score of zero really does mean no marks!! And at 0 kelvin the lowest temperature possible, it's so cold that all molecules have stopped moving.