All data sources are not created equal. Some reference material
has more value than others do. This does not mean that value
equals a greater quantity of information. The actual value
involves the quality of the information provided. Sources of data
can be put into the two general categories of being either
primary or secondary.
A primary data source is something that originates from first-hand
knowledge of the person referenced in the data or from a first-hand
A secondary data source means that the information
is simply second-hand. If you write your own life history,
the data you include would be considered primary. If you
write about incidents in the lives of extended family (which
you did not witness) the data is secondary. The information
in a will is primary. The information in a will abstract book is
secondary. Data on a ship's passenger manifest (a list of
people who boarded the ship before it sailed) is primary but
an index (created by someone compiling the original list)
It is a rare experience, however, to find absolutely pure primary
data sources. Death certificates are good examples of this
concept. The death date has a good chance of being primary.
Other information like the person's place of birth or birth date
might be provided by someone who has no direct knowledge
of these facts making these data secondary.
Information from the federal census also falls into this category
of mixed types of data. For example, the census taker (enumerator)
interviews the wife/mother in a family of five. Most of the
information written by the enumerator is primary since the wife
has first hand knowledge of her life and that of her children.
The information she gives about the birthplace of her husband
or the couple's parents is likely to be secondary.
Of course, all of the information from a census is secondary
unless you are looking at copies of the original returns. Beginning
with the 1880 census, an index called the Soundex coding system
was used to organize some of information. A Soundex version
of the 1880 census was used just with families who had children
under eleven years old in the home.
The existing 1890, 1900 and 1920 census returns are fully
indexed through this system. Only select states of the 1910
census are in the Soundex system. There will be a Soundex
version of the 1930 census.
The list of purely secondary source material includes (but
is not limited to): newspaper articles like obituaries, wedding
announcements, and summaries of real estate transactions;
the index to births, marriages, and deaths kept by clerks of
county courts and at state archives; tombstone information
(unless it explains who provided the data); or anything
abstracted or compiled.
Despite these grand divisions, let it not be misunderstood
that secondary data sources are worthless. Likewise, never
be led to believe that primary data is always accurate. The
art and science of good genealogy operates on the basis
of (1) preponderance and (2) the more preponderance, better
the reliability and validity. It is simply prudent for the
researcher to be acutely aware that everything contained
in a data source should not be treated equally.
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