Introduction to Data

Every sensible decision rests on facts, and facts reach us as data. Long before the term gets a formal definition, we already live by it: a student choosing a college studies the placement record of previous years, the educational qualifications and experience of the faculty, the laboratory and hostel facilities, the fees, and so on. Picking a college is really an act of collecting several kinds of data and analysing them together.

The same pattern repeats at every scale of society:

• Governments systematically collect and record data about the population through a process called the census. Census data carries valuable information that helps in planning and in formulating policies.
• Sports teams rely on it too — the coaching staff analyses the previous performances of opponent teams and builds match strategies from that analysis.
• Banks maintain data about their customers, their account details and every transaction.

All of these examples point to one conclusion: data are needed in every field, and data are crucial for decision making.

Raw data alone cannot decide anything

There is a catch: nobody can take a decision by simply staring at raw data. Return to the college example. Suppose the placement cell has maintained records of about 2000 students placed with different companies at different salary packages over the last 3 years. Looking at that heap of entries, no one can make any meaningful remark about how good the college's placements are. What the college actually does is process and analyse this data, and then present the results in its placement brochure as summaries and visuals that anyone can grasp at a glance.

The lesson generalises: data must be gathered, then processed, then analysed before it can support a decision.

What exactly is data?

In general, data is a collection of characters, numbers and other symbols that represents values of some situations or variables. A small point of grammar worth remembering for exams: data is the plural form; its singular is datum.

Using computers, data are stored in electronic form, because electronic data processing is far faster and easier than manual processing done by people. The Information and Communication Technology (ICT) revolution — driven by the computer, the mobile phone and the Internet — has caused data to be generated in enormous volumes and at a very fast pace.

Everyday examples of data

Data surrounds us in many familiar forms:

• Name, age, gender, contact details and similar particulars of a person
• Transaction data generated through banking, ticketing and shopping — whether online or offline
• Images, graphics, animations, audio and video
• Documents and web pages
• Online posts, comments and messages
• Signals generated by sensors
• Satellite data, including meteorological data, communication data, earth observation data, and so on

Each of these is a value recorded about some situation or variable — and each becomes useful only after it is collected, processed and analysed.