What are (i) primary data? (ii) secondary data? Which of the two -- the primary or the secondary data -- is more reliable and why?

Explanation

(i)Primary data: The data collected by the investigator himself with a definite plan in mind are known as primary data.
(ii)The data collected by someone, other than the investigator, are known as secondary data.
Secondary data should be carefully used, since they are collected with a purpose different from that of the investigator and may not be fully relevant to the investigation.
These data are, therefore, highly reliable and relevant. Secondary data: