Often the choice of what information is translated into an electronic database, index, or list format is largely left to the discretion of the organization, project manager, or individual creating the compilation. Valuable information may be left out due to space or time constraints, or incorrectly indexed due to ignorance on the part of the individual transcriber. Many times this information is the difference between a brick wall in research and a clue to solving a family history mystery.
While it is valuable to know when your ancestors died, it is even more valuable to know the circumstances surrounding their death and who was left behind. One database of early town death records eliminated the cause of death and coroners notes. When viewing the originals, it was found within those notes indications that some people had died by drowning or accidental falls. Deaths by epidemic illnesses were also in the original records, along with notes about next of kin and other relations of the deceased. This information is invaluable when searching for pathways to additional records for research and would have been lost without viewing the originals.
In another example, one compiler's zeal to make information available to the general public for no charge resulted in a large index of vital records from a well known collection being put on-line, but elminated the actual town where the event happened and the book and page numbers where the original information was located. It was this information that made the collection valuable. Researchers using this information at face value could possibly be misled into following an incorrect line with no differentiating town associations for people with the same name and no way to track back to the original information.
The Massachusetts Vital Records to 1850 collection is a great example of why finding original records or supporting documentation for your findings is important. Many people fail to read the "front matter" in these books that explains that the information is taken from a variety of sources, not all from civil records which did not exist officially in Massachusetts until 1841. Many of these records are taken from church, Bible, and other family papers. While these original sources may not exist anymore, they provide clues to further records or family members, in the case of the owners of the Bibles recorded, that can be pursued.
When using any secondary or tertiary record source, it is important to look for pathways to the original records. Read any information that tells what the compilation contains and does not contain, and if the original records are not available, obtain other documentation to corroborate your findings. Viewing the original records can also bring unexpected benefits. Imagine the surprise of one researcher when browsing microfilmed copies of actual census records and realizing that the enumerator, not listed in the abstracts of the records, was actually a relative! There are many reasons to view original records when researching, but the most important one is that it is just good research practice.