Sources: Primary and Secondary Explained

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)

is secondary.

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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