Class 11 Statistics Notes · GSEB

Primary and Secondary Data

Primary and Secondary Data — learn the meaning, differences, and examples of primary and secondary data. GSEB Class 11 Statistics notes.

Last updated: 11 Jul 2026

Notes

Primary Data — Definition and Examples

The data obtained by any statistical inquiry must be correct and proper; otherwise no useful and valid conclusions can be drawn. The data can be primary data or secondary data.

Primary Data

The data originally collected by any authorized agency or investigators for the first time are called primary data.

Examples of Primary Data

1.The data collected by NSSO (National Sample Survey Organization)
2.The data of the population census of India
3.The data relating to death rates and birth rates in India published by the office of the Registrar General of India, New Delhi

Real-Life Connection

When a teacher conducts a survey of student study habits by personally asking each student questions, the data collected is primary data — the teacher is the original collector.

Secondary Data — Definition and Examples

Secondary Data

When an investigator or agency uses the data already collected by any other agency or investigator, then such data becomes secondary data for the users.

Examples of Secondary Data

1.The data regarding birth rate and death rate in India published by the Registrar General of India are reproduced by UNO in the UN Statistical Abstract. For UNO, this becomes secondary data.
2.Data collected by an agency about industries of Gujarat, later used by a research student for statistical analysis — becomes secondary data for the student.

Think about it

Think of it like this: if you write notes from a lecture, those are your primary data. If your friend uses your notes to study, those become secondary data for your friend. Same data, different perspective!

Primary vs Secondary Data — Comparison

Aspect	Primary Data	Secondary Data
Originality	Obtained for the first time; it is original	Not original; it is collected data reused by others
Source of Collection	Collected from the units under inquiry	Obtained from the primary data
Form	Usually in raw form — requires classification and tabulation	Usually in classified and tabulated form
Cost, Time & Energy	Requires large amount of money, time and energy	Requires comparatively very less amount of money, time and energy
⭐ Reliability	Almost reliable	Obtained by individuals or institutions for their own interest; may not be reliable or relevant from the point of view of user's interest or purpose

Key Takeaways

Primary data is collected for the first time by the investigator and is original in nature.
NSSO data, Census data, and birth/death rate data published by the Registrar General of India are examples of primary data.
Secondary data is data originally collected by one agency but reused by another — e.g., UNO reusing India's birth rate data.
Primary data is raw and needs classification; secondary data is already classified and tabulated.
Primary data is more expensive and time-consuming to collect; secondary data is cheaper and faster.
Primary data is almost reliable; secondary data may not be reliable as it was collected for a different purpose.