Posts Tagged ‘ww1’

Canadian self-reported birthday data

Sunday, February 22nd, 2015

In the last post, we saw strong evidence for a “memorable date” bias in self-reported birthday information among British men born in the late 19th century. In short, they were disproportionately likely to think they were born on an “important day” such as Christmas.

It would be great to compare it to other sources. However, finding a suitable dataset is challenging. We need a sample covering a large number of men, over several years, and which is unlikely to be cross-checked or drawn from official documentation such as birth certificates or parish registers. It has to explicitly list full birthdates (not just month or year)

WWI enlistment datasets are quite promising in this regard – lots of men, born about the same time, turning up and stating their details without particularly much of a reason to bias individual dates. The main British records have (famously) long since burned, but the Australian and Canadian records survive. Unfortunately, the Australian index does not include dates of birth, but the Canadian index does (at least, when known). So, does it tell us anything?

The index is available as a 770mb+ XML blob (oh, dear). Running this through xmllint produces a nicely formatted file with approximately 575,000 birthdays for 622,000 entries. It’s formatted in such a way as to imply there may be multiple birthdates listed for a single individual (presumably if there’s contradictory data?), but I couldn’t spot any cases. There’s also about ten thousand who don’t have nicely formatted dd/mm/yyyy entries; let’s omit those for now. Quick and dirt but probably representative.

And so…

There’s clearly a bit more seasonality here than in the British data (up in spring, down in winter), but also the same sort of unexpected one-day spikes and troughs. As this is quite rough, I haven’t corrected for seasonality, but we still see something interesting.

The highest ten days are: 25 December (1.96), 1 January (1.77), 17 March (1.56), 24 May (1.52), 1 May (1.38), 15 August (1.38), 12 July (1.36), 15 September (1.34), 15 March (1.3).

The lowest ten days are: 30 December (0.64), 30 January (0.74), 30 October (0.74), 30 July (0.75), 30 May (0.78), 13 November (0.78), 30 August (0.79), 26 November (0.80), 30 March (0.81), 12 December (0.81).

The same strong pattern for “memorable days” that we saw with the UK is visible in the top ten – Christmas, New Year, St. Patrick’s, Victoria Day, May Day, [nothing], 12 July, [nothing], [nothing].

Two of these are distinctively “Canadian” – both 24 May (the Queen’s birthday/Victoria Day) and 12 July (the Orange Order marches) are above average in the British data, but not as dramatically as they are here. Both appear to have been relatively more prominent in late-19th/early-20th century Canada than in the UK. Canada Day/Dominion Day (1 July) is above average but does not show up as sharply, possibly because it does not appear to have been widely celebrated until after WWI.

One new pattern is the appearance of the 15th of the month in the top 10. This was suggested as likely in the US life insurance analysis and I’m interested to see it showing up here. Another oddity is leap years – in the British data, 29 February was dramatically undercounted. In the Canadian data, it’s strongly overcounted – just not quite enough to get into the top ten. 28 February (1.28), 29 February (1.27) and 1 March (1.29) are all “memorable”. I don’t have an explanation for this but it does suggest an interesting story.

Looking at the lowest days, we see the same pattern of 30/xx dates being very badly represented – seven of the ten lowest dates are 30th of the month…. and all from days where there were 31 days in the month. This is exactly the same pattern we observed in UK data, and I just don’t have any convincing reason to guess why. The other three dates all fall in low-birthrate months,

So, in conclusion:

  • Both UK and Canadian data from WWI show a strong bias for people to self-report their birthday as a “memorable day”;
  • “Memorable” days are commonly a known and fixed festival, such as Christmas;
  • Overreporting of arbitrary numbers like the 15th of the month are more common in Canada (& possibly the US?) than the UK;
  • The UK and Canadian samples seem to treat 29 February very differently – Canadians overreport, British people underreport;
  • There is a strong bias against reporting the 30th of the month particularly in months with 31 days

Thoughts (or additional data sources) welcome.

When do you think you were born?

Monday, February 16th, 2015

Back in the last post, we were looking at a sample of dates-of-birth in post-WWI Army records.

(To recap – this is a dataset covering every man who served in the British Army after 1921 and who had a date of birth in or before 1900. 371,716 records in total, from 1864 to 1900, strongly skewed towards the recent end.)

I’d suggested that there was an “echo” of 1914/15 false enlistment in there, but after a bit of work I’ve not been able to see it. However, it did throw up some other very interesting things. Here’s the graph of birthdays.

Two things immediately jump out. The first is that the graph, very gently, slopes upwards. The second is that there are some wild outliers.

The first one is quite simple to explain; this data is not a sample of men born in a given year, but rather those in the army a few decades later. The graph in the previous post shows a very strong skew towards younger ages, so for any given year we’d expect to find marginally more December births than January ones. I’ve normalised the data to reflect this – calculated what the expected value for any given day would be assuming a linear increase, then calculated the ratio of reported to expected births. [For 29 February, I quartered its expected value]

There are hints at a seasonal pattern here, but not a very obvious one. January, February, October and November are below average, March and September above average, and the rest of the spring-summer is hard to pin down. (For quite an interesting discussion on “European” and “American” birth seasonality, see this Canadian paper)

The interesting bit is the outliers, which are apparent in both graphs.

The most overrepresented days are, in order of frequency, 1 January (1.8), 25 December (1.43), 17 March (1.33), 28 February (1.27), 14 February (1.22), 1 May (1.22), 11 November (1.19), 12 August (1.17), 2 February (1.15), and 10 October (1.15). Conversely, the most underrepresented days are 29 February (0.67 after adjustment), 30 July (0.75), 30 August (0.78), 30 January (0.81), 30 March (0.82), and 30 May (0.84).

Of the ten most common days, seven are significant festivals. In order: New Year’s Day, Christmas Day, St. Patrick’s Day, [nothing], Valentine’s Day, May Day, Martinmas, [nothing], Candlemas, [nothing].

Remember, the underlying bias of most data is that it tells you what people put into the system, not what really happened. So, what we have is a dataset of what a large sample of men born in late nineteenth century Britain thought their birthdays were, or of the way they pinned them down when asked by an official. “Born about Christmastime” easily becomes “born 25 December” when it has to go down on a form. (Another frequent artefact is overrepresentation of 1-xx or 15-xx dates, but I haven’t yet looked for this.) People were substantially more likely to remember a birthday as associated with a particular festival or event than they were to remember a random date.

It’s not all down to being memorable, of course; 1 January is probably in part a data recording artefact. I strongly suspect that at some point in the life of these records, someone’s said “record an unknown date as 1/1/xx”.

The lowest days are strange, though. 29 February is easily explained – even correcting for it being one quarter as common as other days, many people would probably put 28 February or 1 March on forms for simplicity. (This also explains some of the 28 February popularity above). But all of the other five are 30th of the month – and all are 30th of a 31-day month. I have no idea what might explain this. I would really, really love to hear suggestions.

One last, and possibly related, point – each month appears to have its own pattern. The first days of the month are overrepresented; the last days underrepresented. (The exception is December and possibly September). This is visible in both normalised and raw data, and I’m completely lost as to what might cause it…

Back to the Army again

Saturday, January 24th, 2015

In the winter of 1918-19, the British government found itself in something of a quandary. On the one hand, hurrah, the war was over! Everyone who had signed up to serve for “three years or the duration” could go home. And, goodness, did they want to go home.

On the other hand, the war… well it wasn’t really over. There were British troops fighting deep inside Russia; there were large garrisons sitting in western Germany (and other, less probable, places) in case the peace talks collapsed; there was unrest around the Empire and fears about Bolsheviks at home.

So they raised another army. Anyone in the army who volunteered to re-enlist got a cash payment of £20 to £50 (no small sum in 1919); two month’s leave with full pay; plus comparable pay to that in wartime and a separation allowance if he was married. Demobilisation continued for everyone else (albeit slowly), and by 1921, this meant that everyone in the Army was either a very long-serving veteran, a new volunteer who’d not been conscripted during wartime (so born 1901 onwards) or – I suspect the majority – re-enlisted men working through their few years service.

For administrative convenience, all records of men who left up to 1921 were set aside and stored by a specific department; the “live” records, including more or less everyone who reenlisted, continued with the War Office. They were never transferred – and, unlike the pre-1921 records, they were not lost in a bombing raid in 1940.

The MoD has just released an interesting dataset following an FOI request – it’s an index of these “live” service records. The records cover all men in the post-1921 records with a DoB prior to 1901, and thus almost everyone in it would have either remained in service or re-enlisted – there would be a small proportion of men born in 1900 who escaped conscription (roughly 13% of them would have turned 18 just after 11/11/18), and a small handful of men will have re-enlisted or transferred in much later, but otherwise – they all would have served in WWI and chosen to remain or to return very soon after being released.

So, what does this tell us? Well, for one thing, there’s almost 317,000 of them. 4,864 were called Smith, 3,328 Jones, 2,104 Brown, 1,172 Black, etc. 12,085 were some form of Mac or Mc. And there are eight Singhs, which looks like an interesting story to trace about early immigrants.

But, you know, data cries out to be graphed. So here’s the dates of birth.

Since the 1900 births are probably an overcount for reenlistments, I’ve left these off.

It’s more or less what you’d expect, but on close examination a little story emerges. Look at 1889/90; there’s a real discontinuity here. Why would this be?

Pre-war army enlistments were not for ‘the duration’ (there was nothing to have a duration of!) but for seven years service and five in the reserves. There was a rider on this – if war broke out, you wouldn’t be discharged until the crisis was over. The men born 1900 would have enlisted in 1908 and been due for release to the reserves in 1915. Of course, that never happened… and so, in 1919, many of these men would have been 29, knowing no other career than soldiering. Many would have been thrilled to get out – and quite a few more would have considered it, and realised they had no trade, and no great chance of good employment. As Kipling had it in 1894:

A man o’ four-an’-twenty what ‘asn’t learned of a trade—
Except “Reserve” agin’ him—’e’d better be never made.

It probably wasn’t much better for him in 1919.

Moving right a bit, 1896-97 also looks odd – this is the only point in the data where it goes backwards, with marginally more men born in 1896 than 1897. What happened here?

Anyone born before August 1896 was able to rush off and enlist at the start of the war; anyone born after that date would either have to wait, or lie. Does this reflect a distant echo of people giving false ages in 1914/15 and still having them on the paperwork at reenlistment? More research no doubt needed, but it’s an interesting thought.

Letters from the West

Sunday, November 11th, 2012

The British Library has recently released the first tranche of some material it digitised as part of the Europeana 1914-1918 program. Most of this first installment involves papers from the India Office Records, which (for various reasons) ended up being transferred from the FCO to the British Library rather than the National Archives. As the Indian Government was responsible for India’s participation in the war, they include all sorts of unexpected primary sources rather than the more usual printed histories – official reports, intelligence briefings, policy papers, etc.

But the most interesting, by far, are the “Reports of the Censor of Indian Mails in France”. The system of censorship in force at the time had two goals – the first was the most obvious, to prevent the transmission of negative rumours or sensitive information, either by obscuring the comments or by returning the letters unsent. The second was more subtle; the censors who were reading the letters used them to prepare reports on morale, the reaction of front-line soldiers to news, and the like. Inbound mail was also censored, with much the same effect.

The Indian reports contained a brief summary of themes and comments in the censored mail for the period, along with a selection of translated extracts giving the name of the sender and recipient, and a note of the language they had written in. The originals weren’t kept, and the chances are that very few survive anywhere.

Many letters deal with the fighting, with reports of the war. Others are simply slices of life, reports of the strange world far from home:

I had an opportunity of seeing London. It is an enormous city. It took about an hour and a half for the train to go through the city without stopping. The buildings are high, the streets are very clean. There are many big factories. Many kinds of gardens, fields without any walls, short cows with long hair and short horns are some of the objects that came to my notice. (“a Mahratta Brahmin”, 21/1/15)

No one has any clue as to the language of this place. Even the British soldiers do not understand it. They call milk “doolee” and water “deolo” [du lait, de l’eau]. There is much comeliness in this country. The people dress themselves like the English. Of black men they think a great deal. No one keeps “parda” as we do. The country is a very open one. The ladies shake hands freely. They are not bashful about this. They do as the English do. (“X.Y., a wounded Sikh”, 27/1/15)

We enjoyed the Saloono festival as best as it could be enjoyed by a foreigner in a distant country far from home. Here we managed to get camphor, sandal wood and other necessities of “Hawan” which was done with Vedic mantras in France, which the French people might never have expected. We also get “saimis” here, they are manufactured in Paris as well as in Italy and are sold in small packets. (Ram Seran Das, August 1915)

The French language:
Kya, tum mere sath aoge? = Walé wo wené éwac má?
Tumhara ghar kidhar hai = U é watr mézon?
Main tum ko pyar karta hun = Y ém wu boku. (Jemadar Sohbat Khan, 29/8/15)

When this letter was written we four, viz, Gul Din, Gul Shah, Rakib Shah, and I were sitting under a tree, eating apples and pears and had made a pipe out of an empty shell-case and were smoking, with the pipe standing in front of us. (Jemadar Zar Gir, 57th Rifles, 30/8/15)

In this country rain falls every day. The country is cold and abounds in fruit. (Sowar Sharif Khan, 13/9/15)

As to your request to send you a copy of the Qu’ran, I have already written and told you that I cannot get one here. What is the use of repeating it? If I could get one here, I would send it. You say the Qu’ran can be got in London, but London is 52 miles from here [Brighton] and we do not go there. (Khadim Ali Khan, 17/10/15)

These are the result of skimming two or three volumes; there’s a wealth of social history buried in these papers, and it would really reward some intensive reading.

They’re all listed through the Digitised Manuscripts interface, which is a little tricky to use; for reference, here’s a full index of the digitised papers by date covered: