There exists several debatble categorization methods of data.

The first widely spread theory, or level of measurement, is by S. Stevens. The theory categorizes data into the four types, nominal, ordinal, interval, and ratio.

Other methods are proposed for other fields of research. For example, N. R. Chrisman proposed a different method for cartography. However, these are not generic enough for data science for data science are more general than a specific field of research.

For the purpose of machine learning, many statistical data types has been proposed. Some examples of data types and their relations with level of measurement are shown in the following chart.

Data types and level of measurement. on plectica