broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe research material is material the social researcher collects himself through such methods as questionnaires, observation, interviews etc.
However there is also a wealth of information available to the researcher in the form of broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe sources. These include legal documents, parish records, official broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe, diaries, novels auto biographies, newspapers, TV programmes, film. The data within secondary sources is referred to as secondary broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe.

Secondary sources are often used when the researcher is unable to obtain primary data or to back up and broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe primary data they have collected through their own direct research.

Primary data may not be available in the following circumstances:
When historical data is required and the participants are broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe
When the researcher is studying a culture too broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe to visit in person
When the activities being studied are illegal and it is broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe for the researcher to collect primary data
When a "closed group" e.g. monks in a monastery are being studied and the researcher is not broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe to enter to collect primary data.

Secondary data can be useful because:
Official statistics cover a much broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe research base than the individual researcher could ever cover on his own
Published data is broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe to research
Such data is easy to obtain
The information covers a long time span so broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe can be established.

The usual types of secondary data used by social researchers include:

Official statistics
The broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe media
Diaries
broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe history (spoken recorded interviews or transcripts of them)
Letters
Fiction
The existing work of other social broadercheapcorroboratedatadeaddistantmassOralpermittedPrimaryresearcherssecondarystatisticstrendsunsafe.