Monday, January 07, 2019

Calculating Birth Date Ranges

In my last post, Visualizing Birth Evidence, I used date ranges calculated from an age on a particular date. It took me a long time to wrap my mind around this but now that I understand how it works, I find it much more useful than just subtracting an age from a year and it isn't that much harder to do.

Let's use Frank M. Smith as an example. On 2 July 1885, he stated, under oath, that he was forty-eight years old. [1]

Subtracting 48 from 1885, I get 1837. (To easily do this in my head, I subtract 40 from 1885 and get 1845. Then, because I can't take 8 from 5, I take 8 from 15 and get 7 and just reduce the 10s by 1 to get 38 instead of 48. And, I try to remember to add things back up to double-check my mental math.)

So, if 2 July 1885 happened to be Frank's birthday, he would have been born on 2 July 1837.

And, in fact, if he had been born any time between 1 January 1837 and 2 July 1837, he would have already turn 48 by 2 July 1885.

But what if he happened to have been born in the second half of the year?

If he was 48 on July 2, looking forward to celebrating his 49th birthday between 3 July 1885 and 31 December 1885, that would mean he was born in 1836.

So, the birth date range for Frank, who was 48 on 2 July 1885 is 3 July 1836 to 2 July 1837.

Let's do one more example.

When Frank registered to vote on 16 October 1888, he stated that he had been in the city of Chicago for 52 years. [2] He was born there, so, theoretically, that would have been  his age.

1888 minus 52 equals 1836. So, the date range for Frank's birth calculates to 17 October 1835 to 16 October 1836.

Now let's look at these two date ranges together.


1835
1836
1837
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12


















Proof of Heirship














1888 Voter Registration



































Published Family History






If -- and that's a big if -- Frank's age was stated correctly on the two dates, then comparing the two narrows his birthdate to between July 1836 and October 1836. Knowing that makes it easy to see that the exact birth date stated in a published family history falls squarely into the range of possibility. [3]

Some thing to keep in mind:

1) The approach is only as good as the information it's based on.

2) Date ranges are particularly useful for comparing age information from records that were created in different months.

3) When calculating date ranges from census records, the census dates vary, depending on the census year. (For a quick reminder, just Google "u s census dates.") Also, census takers might have recorded ages as of the census date or as of the date they visited--no matter what the instructions asked them to do.

And where can we find age information for particular dates in Chicago records?

Quickly brainstorming, let's see ...

  • marriage licenses
  • parent information on children's birth records
  • death certificates
  • voter registration (if the person was born in Chicago)
  • proof of heirship interviews in probate files
  • census records
  • legal documents
What have I forgotten? Leave a note in the comment section to let us know!

So, in summary, here's the way that I've finally wrapped my mind around the idea of calculating birth date ranges from an age on a particular day, month, and year:

Subtract the age from the particular year to get the end year. The end year is the same as the particular day.

Subtract 1 from the end year to get the start year.

The start day is the day after the particular day.
__________

1.     Cook County, Illinois, probate file no. 4-2790 (1885), Marcia M. Smith, proof of heirship, 2 July 1885; Cook County Circuit Court Archives, Chicago.

2.     "Chicago, Illinois, Voter Registration, 1888," database with images, Ancestry (https://search.ancestry.com/search/db.aspx?dbid=5991 : accessed 5 November 2018), entry for Frank M. Smith born in Illinois.

3.     American Ancestry: Giving the Name and Descent, in the Male Line, of Americans Whose Ancestors Settled in the United States Previous to the Declaration of Independence, A. D. 1776, Vol. IX (Albany, N.Y.: Joel Munsell’s Sons, 1894), 132; digital image, Google Books (https://books.google.com/books?id=7Ew7AQAAIAAJ : accessed 5 November 2018).

Sunday, January 06, 2019

Visualizing Birth Evidence

So, prompted by some work I've been doing on trying to figure out birth, marriage, and death dates for a number of my husband's Chicago relatives, I've come up with a way to visually compare the evidence. It isn't a ground breaking approach--I'm sure a lot of you do something similar--but it's pretty simple and I'm finding it really helpful so I thought I'd share.

First of all, in the three years that I've been working on learning to "do it right," I've fallen into a routine of gathering evidence into a table to help me wrap my mind around it. Each line includes a year for sorting purposes, a citation, the information, and quick notation to help me consider the quality of the source, the information, and the evidence. The table is for my own use and it looks something like this:

Birth Date Evidence for Frank M. Smith

0SourceInformation
Source
O/D/A
Info
P/S/I
Evidence
D/I/N
18501850 U. S. census, Cook County, Illinois, population schedule, Chicago, First Ward, n.p., dwelling 275, family 293, F (male) Smith; digital image, FamilySearch (https://www.familysearch.org : accessed 7 May 2018), citing NARA microfilm publication M432, roll 102.Age 13 [born 2 Jun 1836 to 1 Jun 1837]
O
I
D
18601860 U. S. census, Cook County, Illinois, population schedule, Chicago, First Ward, p. 36 (penned), dwelling [illegible], family [illegible], Jas A. Smith; digital image, FamilySearch(https://www.familysearch.org/ark:/61903/1:1:MXH7-C5Q : accessed 7 May 2018), citing NARA microfilm publication M653, roll 164Age 23 [born 2 Jun 1836 to 1 Jun 1837]
O
I
D
1885Cook County, Illinois, probate file no. 4-2790 (1885), Marcia M. Smith, proof of heirship, 2 July 1885; Cook County Circuit Court Archives, Chicago.Informant, Frank M. Smith stated that he was forty eight years on 2 July 1885. [born 3 July 1836 to 2 July 1837]
D
S
D
1888"Chicago, Illinois, Voter Registration, 1888," database with images, Ancestry (https://search.ancestry.com/search/db.aspx?dbid=5991 : accessed 5 November 2018), entry for Frank M. Smith born in Illinois.Applied 16 Oct 1888; had been in precinct, county, and state for 52 years [born 17 Oct 1835 to 16 Oct 1836]
D?
S
I
1894American Ancestry: Giving the Name and Descent, in the Male Line, of Americans Whose Ancestors Settled in the United States Previous to the Declaration of Independence, A. D. 1776, Vol. IX (Albany, N.Y.: Joel Munsell’s Sons, 1894), 132; digital image, Google Books (https://books.google.com/books?id=7Ew7AQAAIAAJ : accessed 5 November 2018)."Francis Marion Smith, born in Chicago, Sep 27, 1836"
A
I
D
1899Rosehill Cemetery Office (Chicago, Illinois), burial record, int. no. 48981, Francis Smith.Age 63; died 13 October 1899 [born 14 Oct 1835 to 13 Oct 1836]
D
I
D
1899"Chicago death certificates, 1878-1915," FamilySearch(https://www.familysearch.org/search/catalog/42925) > 1033071 > image 1265, Chicago death certificate no. 18070 (13 October 1899), Francis M. Smith.Age 63; died 13 October 1899 [born 14 Oct 1835 to 13 Oct 1836]
O
I
D
1899"Frank Smith Passes Away," The Chicago Tribune, 14 October 1899, p. 7, col. 1; digital image, Newspapers.com (https://www.newspapers.com/image/349269502/ : accessed 9 April 2018).Born in Chicago in 1836.
O
I
D

But, as you can see, even though the evidence is neatly summarized in one place, it's still hard to grasp what's what.

Here's where a visual summary like the one below comes in.

1835
1836
1837
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12


















Proof of Heirship














Death Certificate























Burial Record


























Obituary





























1850 Census























1860 Census















1888 Voter Registration



































Published Family History






Basically, it's a table that allows me to plot dates or calculated date ranges from the sources listed in the evidence table. It took a bit of tweaking to set up the template, but now that I have it, it's pretty quick and easy to fill it in. Sometimes I use color, but this one happens to be grayscale.

In this case, it shows, at a glance, that the exact date published in the family history falls into the ranges suggested by information from every other source collected to date. It also shows, by way of the shading, which sources should be the most reliable. Frank was the informant for his age on the proof of heirship record and for his length of residence on the voter registration record (which should have been his age because he was born in Chicago) so I've colored those squares darker than the records that have unknown informants.

Here's another example:

Birth date Evidence for Charles B. Smith

1827
1828
1829
1830
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12

















1850 Census



































1860 Census























1870 Census



























































1880 Census
























Proof of Heirship



















































Death Certificate






































Burial Record






































Obituary
















Parents’ Marriage
Parents’ Marriage



















































Brother Born






















Possible Birth


















The parents probably married in 1828, but one source suggests 1829 and it can't be completely ruled out, thus the two entries in yellow/orange. The brother's birth month and year, shown in green, is very likely correct. His death at sixteen months was recorded in a church register and reported in a local newspaper. 

Knowing these two things, it's easy to see that the birth date range suggested by the age in the 1870 census is an outlier that doesn't work well with the parents' probable marriage year.  And, the birth dates and date ranges suggested by the 1880 census and the death-related records aren't feasible. I'm quite sure the two children were born to the same mother and it's very unlikely she gave birth to one child five months after another.

But, if the exact birth date provided in the obituary is off by a year--the hypothesized date is indicated in blue--then it would be consistent with his age provided by a brother in the proof of heirship document and with his age as recorded in two census records. 

It would be necessary, of course, to examine specific evidence in detail, in writing, before drawing any conclusions, but the visual makes it easy to see a path that a proof argument might take.

I'm curious to know how the rest of you approach this topic. If you can offer further advice for sorting through birth, marriage, and/or death date evidence, please post a comment. Thanks!


Calculating Birth Date Ranges

In my last post, Visualizing Birth Evidence , I used date ranges calculated from an age on a particular date. It took me a long time to wra...