April 28, 2005


Scotland's population swelled by largest immigration in 50 years (STEPHEN MCGINTY, 4/28/05, The Scotsman)

SCOTLAND’S population increased significantly last year as a result of the largest net rise in immigrants in more than 50 years.

According to new figures published by the General Register Office (GRO) for Scotland, 27,200 more people arrived in Scotland than departed from it between July 2003 and July 2004. This swelled the nation’s population to 5,078,400.

Taking into account births and deaths, the total increase in the Scottish population was about 21,000...

You do the math.

Posted by Orrin Judd at April 28, 2005 8:25 AM

I know this is one of your favorite topics so I have a question. I know the replacement number of chidren is 2.1 per woman. Is that figure calculated using only women of childbearing age (defined however) or total adult women? or total females? What is the denominator?

Posted by: Brandon at April 28, 2005 9:52 AM

Total number of women. I.e., the average number of children every woman should have during her lifetime is 2.1 in order to keep the population stable.

Posted by: Annoying Old Guy at April 28, 2005 11:03 AM

2.1 based on 2 children needed to replace the father and mother and .1 to deal with people that die early due to disease, accidents, etc.

As for Scotland the article notes that most of the immigrants were from the new EU countries (Poland, Czech, etc). As long as they don't mind wearing kilts it shouldn't be an issue.

Posted by: AWW at April 28, 2005 11:31 AM

Few people are aware that there is a long tradition of Polish bag pipes. I forget hpow it is different from the Scottish ones, but similar enough to be mistaken at first glance.

Posted by: oswald booth czolgosz at April 28, 2005 11:36 AM

Come to think of it, the 2.1 is only valid assuming a 50/50 split between boys and girls; if the split were 60/40 it would be more like 2.6 to maintain.

Posted by: Mike Earl at April 28, 2005 12:49 PM

If it is total women, then would an aging female population skew the statistics? Total women could increase while total children remained the same - causing the average to drop. That might still result in a population decline but it would be more of a short-term leveling off rather than a continuous decrease.

Posted by: Brandon at April 28, 2005 12:54 PM

Brandon -

Yes, but then the younger cohort of women would have to make up for it; i.e. produce 2.6 (say) children per nubile woman, and there is no evidence they are doing this. If the younger cohort starts to again produce 2.1, then the population will stabilized, but decreased.

Posted by: Bruce Cleaver at April 28, 2005 3:19 PM

Ahem. That last sentence should read, "..will be stabilized, but decreased."

Posted by: Bruce Cleaver at April 28, 2005 3:27 PM


I don't think your point is really different from mine. It does seem obvious that Europe is headed for a population decrease (among native Europeans anyway.) I'm just wondering if the statistics don't point toward a slight decrease more than a drastic one.

Plus, since the child replacement rates I've seen run from 1.3-2.0, at what point would an aging effect no longer be important? I was hoping someone here could point me to a more in-depth statistical analysis.

Posted by: Brandon at April 28, 2005 3:34 PM

Brandon--I think you've mistaken what the statistic is. It is not (#children/#women), but rather (#children/1 woman's lifetime), so there isn't any aging effect.

Posted by: b at April 28, 2005 3:42 PM



Suppose population were to stay the same but forty years from now 90% of those under 50 were Muslims and Eastern Europeans? What's left of France, Germany, Scotland, etc.?

Posted by: oj at April 28, 2005 3:47 PM

Brandon - If the birth rate is 1.4 per woman, 2.1 is replacement, and the average age at which the mother gives birth is 30, then every 30 years the number of mothers declines by 1/3. After 90 years, the population of birth-mothers has declined to 8/27 of what it used to be, for a 70% decrease.

Posted by: pj at April 28, 2005 3:53 PM


Well it actually turned out to be average number of babies born to women during their reproductive years. So you're right, there doesn't seem to be an aging effect there. I do wonder how they determine that figure though?


Thanks for the link. I don't know what will become of France, etc, but the site projected a decrease in all nations, not just European ones. So fewer immigrants will be coming into Europe

Posted by: Brandon at April 28, 2005 5:21 PM


How does that follow? Would you stay in Somalia or go take over an empty Holland?

Posted by: oj at April 28, 2005 5:28 PM

Brandon: I am very curious how you think a woman could have children during her non-reproductive years...

Posted by: b at April 28, 2005 6:19 PM


Immigrants have to come from a pool of people. If that pool is smaller, then the number of immigrants will be smaller. So do you think that Europe is going to stay filled with people, but Africa is going to empty out? Besides, I hear Somalia is lovely this time of year.


Definitions are the key to statistics. They must be precise. Otherwise this stuff happens:


Posted by: Brandon at April 28, 2005 7:03 PM

So what? That just shows that we're getting to the point where medicine can make a woman's reproductive years equal to her lifetime minus the first dozen years or so. If all of a sudden in Ireland every 66 year old woman starts having kids, you better count them in your total fertility rate if you want to accurately predict demographic trends...

Posted by: b at April 28, 2005 7:08 PM


Yes, there'll be more people and less Europeans.

Posted by: oj at April 28, 2005 7:41 PM

Brandon -

I think in my previous post, I answered a different question than the one you asked...

Total Fertility Rate must be computed using only childbearing years, else the scenario you described due to aging would indeed have to be accounted for (although it wouldn't be too hard if the older cohort doesn't radically increase its lifespan compared to previous generations).

I found much more info than anyone could ever want at this link:


Roughly, they use ages 15-44 for computation.

I will note the example in the link bemoaned the fact that 1996 (the last year of measurement) had the lowest TFR in Pennsylvania since 1950!

Posted by: Bruce Cleaver at April 28, 2005 9:36 PM