Some people eat, sleep and chew gum, I do genealogy and write...

Tuesday, December 18, 2018

On the Inexactness of dates in genealogy

It is not unusual for a genealogical researcher to find several different historical documents with different dates for the same event, such as a birth date or death date. Without spending a lot of time hand-wringing, you should remember Rule Two of the Rules of Genealogy: Absence of an obituary or death record does not mean the person is still alive. A corollary to this Rule is that multiple differing records of the same event do not change the actual date of the event.

When confronted with this situation, you may have to simply assume that the event occurred sometime between the first and last date recorded. However, close analysis of each of the records may show which one, if any, is the most reliable. For example, a death record may contain a birth date calculated from the assumed age at death. Another common example is the fact that birth dates in census records may also be calculated from the age given on the date of the census and are commonly off one year. Calculated dates are "acceptable" as long as they are clearly indicated as calculated.

As I point out in the expanded version of Rule Two, referenced above, becoming fixated on finding a record for an exact date is counterproductive. In fact, historical events such as the calendar change from the Julian Calendar to the Gregorian Calendar created a patchwork of dates depending on when the change went into effect in a particular country. Dates that were recorded from memory are particularly susceptible to inaccuracy. Returning to the issue of census records, most of these records rely on information supplied by the individual or individuals who are subject to the census. It is common for one person to supply information about other family members and no attempt is made, in almost all cases, to verify the information supplied.

It is not unusual for individuals to lie about dates. For example, it is not uncommon for those enlisting in one or the other of the military services to misrepresent their age. Also, the ages given when applying for a marriage license are also suspect and older people may or may not provide an enhanced date of birth. For example, if we find the date of the birth of a child that seems to indicate that the mother was too young or old to have children, it is not a good idea to immediately remove the child from the family, because the date of birth or age of the mother might be wrong.

Estimated dates may be useful for research purposes but may be misleading if left as recorded dates in family records. Genealogists have used "ballpark" dates such as estimating the age of the mother from the birth of the first child or estimating a marriage age based on the local custom.

The further back in history we go, the more likely it is that any particular date may inaccurate. Unfortunately, once we get really far back in time, some of the dates become so widely used and believed that questioning the date can be controversial. This may also occur with more recent dates when family tradition has established a certain date as a fact and later research shows that the date is unreliable.

Since both names and dates can be subject to inexactness, genealogists need to rely on the location of events as the one non-negotiable constant. It is evident, that many of the places recorded in family histories are imprecise but of the three major issues of name, date, or place, the most important is the place. At least one place of at least one event in a person's life must be identified or there is always a major possiblity of having choosen the wrong person.


  1. Event dates may be inexact or suspect, but the relationships between events (e.g. Baptism AFTER birth, etc) are generally easier to assert and more reliable. STEMMA is one of the few (only?) data models that embraces this part of historical data. Unfortunately, because GEDCOM didn't do it then no one else seems to. Here's a question for your other readers James: I recently came across a birth in Feb 1752 and the corresponding baptism in Dec 1752. How many people (incl. online providers) would consider that to be an error? Anyone worked out the reason for this? :-)

    1. I know how that works, let's see if someone else wants to work it out.

    2. Of course, the problem would make more sense if I re-read it before posting it. The birth was in Dec 1752 but the baptism was in Feb 1752. Anyone want to have a shot?

    3. And to add to it, in what will be America, 1752 was the date when the date changed. I do not know of the tip of my head when it went into effect (Day and Month), but that would explain it. Maybe.

    4. The year should have given people a clue. The 'Calendar (New Style) Act 1750' actually had two parts: changing the start of the civil year from March 25 to January 1, and adopting the Gregorian calendar in preference to the older Julian calendar. The changes were adopted by Britain (and its colonies) in 1752, resulting in 1751 being a short year (because it didn't run its full term to the following March), and 1752 was a short year because 11 days were dropped in September in order to accommodate the new calendar. Hence, the baptism entry I saw was written in the "old style" with a year that ran March-to-March, meaning that Feb 1752 came AFTER Dec 1752.

  2. My husband's grandmother lived to be 97. She died a few weeks before her 98th birthday. As she got older, she got in the habit of embellishing her age. She would just go ahead a claim to be a year older than she was just because it was almost her birthday. She did this for the last few years of her life. I have one of the last quilts that she made. Embroidered on the back is her name and age - 98, except she was never 98. Trust nothing, not even quilts!!!

  3. Is that necessarily automatically an error? No. It most certainly can be however.

    December 1752 was 10 months after February 1752. However the problem is that December 1752 was also 2 months before February 1752. If the events took place in England then it would definitely be an error, but if the events took place in Scotland it would definitely not be an error.

    How about this for a convoluted one? How about if a person was born in January 1753 on a farm just north of the Scottish border but the nearest parish church was in England and the child was christened in a English village church in March 1752? Perfectly possible, perfectly correct and intensely confusing for the vast majority of people.