# Classification of Data

The process of arranging data into homogenous groups or classes according to some common characteristics present in the data is called classification.

For example: During the process of sorting letters in a post office, the letters are classified according to the cities and further arranged according to streets.

Bases of Classification

There are four important bases of classification:

(1) Qualitative Base   (2) Quantitative Base    (3) Geographical Base (4) Chronological or Temporal Base

(1) Qualitative Base

When the data are classified according to a quality or attribute such as sex, religion, literacy, intelligence, etc.

(2) Quantitative Base

When the data are classified by quantitative characteristics like height, weight, age, income, etc.

(3) Geographical Base

When the data are classified by geographical regions or location, like states, provinces, cities, countries, etc.

(4) Chronological or Temporal Base

When the data are classified or arranged by their time of occurrence, such as years, months, weeks, days, etc.

For example: Time series data.

Types of Classification

(1) One -way Classification

If we classify observed data keeping in view a single characteristic, this type of classification is known as one-way classification.

For example: The population of the world may be classified by religion as Muslim, Christian, etc.

(2) Two -way Classification

If we consider two characteristics at a time in order to classify the observed data then we are doing two way classification.

For example: The population of the world may be classified by religion and sex.

(3) Multi -way Classification

We may consider more than two characteristics at a time to classify given or observed data. In this way we deal in multi-way classification.

For example: The population of the world may be classified by religion, sex and literacy.