Statistics 

Statistics is the formal science of making effective use of numerical data relating to group of individuals or experiments. It deals with all aspects, including the collection, analysis and interpretation of data, and also the planning of the collection of data, in terms of the design of surveys and experiments.

A statistician is someone who is particularly versed in the ways of thinking necessary for the successful application of statistical analysis. Often such people have gained this experience after starting work in number of fields. This is also a discipline called mathematical statistics, which is concerned with the theoretical basis of the subject.

Data is normally classified into two types: Primary data and Secondary data. The primary data is that data which is collected by the person himself for his own personal use, while secondary data is that data which is collected by others and used by someone else for his or her use. It may be data collected form the books, newspaper, internet or any other sources.

The data may be in the form of raw or grouped. The data which is not arranged in any form is known as the raw data and the data which is arranged in any definite pattern is known as the grouped data.