What is data?

Navya and Naresh cannot agree. Naresh thinks cricket is the most popular game in their class; Navya likes hockey best. Guessing will not settle it. So they go to every student, ask each one their favourite game, and write the answers in a list.

That list is data. Any collection of facts, numbers, measures or observations that tells us something is called data. Your classmates' favourite colours are data. The weights of every student in your class are data too. Your phone's weather app says '80% chance of rain' because of data collected over many years.

Data helps us decide. A principal wants to buy ice cream for the school, but buying one flavour is cheaper than buying many. So someone asks every child, notes the answers, and buys the flavour most children chose.

Some questions can only be answered by collecting data. Pari has four questions:

• 'What is the most popular TV show among my classmates?' needs data: she must ask people.
• 'How much water is wasted in my locality?' needs data: she must measure.
• 'When did India get independence?' and 'What is the capital of India?' are single known facts: she can look them up. There is nothing to collect.

A good test: if the answer depends on asking many people, counting or measuring, you need to collect data. If it is one fact that is already known, you do not.