Primary Data and Secondary Data

Primary Data

Primary data refers to the data collected for the first time by an investigator or an agency specifically for a particular statistical enquiry.

It is original in nature and is collected directly from the source for analysis.

Key points:

• Collected first-hand by the investigator
• Original and fresh data
• Collected for a specific purpose
• Generally more reliable and accurate

Example:

Population data collected directly by the Census Department during a census.

Secondary Data

Secondary data refers to the data already collected, processed, and published by some other agency and later used by another investigator for statistical analysis.

Key points:

• Not original to the present investigator
• Collected by some other agency
• Can be published or unpublished
• Used for a purpose different from the original one

Example:

Census data published by the Government and later used by researchers or international organizations like the UN.