"researchers usually start their investigation by examining some of the rich variety of low-cost and readily available "secondary" data, then collect "primary" data if the needed data don't existing or are dated, inaccurate, incomplete or unreliable."
Primary data will be data that you gather particularly with the end goal of your examination venture. An advantage of primary data is that it is particularly custom fitted to your examination needs. A weakness is that it is costly to acquire.
Secondary data alludes to information which is gathered by somebody who is somebody other than the client. Regular sources of secondary data for sociology incorporate censuses, data gathered by government divisions, hierarchical records and information that was initially gathered for other research purposes.