Wikipedia:Reference desk/Archives/Miscellaneous/2016 February 26

= February 26 =

Sociological theory about how wealthy nations obtained wealth from other lands of other peoples
Six or seven years ago, I remember reading a heavy sociology textbook on my own time, because I thought the theories were cool, and one impression that I had was that many theories in sociology seemed to support opposing views, as in they were directly opposed to each other. But anyway, one theory was about the wealth of present-day wealthy nations and how they used the wealth from other lands for their own gain. Does anybody know the name of the theory? 140.254.70.33 (talk) 13:18, 26 February 2016 (UTC)


 * That sounds like the economic theory known as mercantilism. -- Jayron 32 13:42, 26 February 2016 (UTC)


 * Colonialism is of course how many of the countries that are rich today got wealth from other lands. SemanticMantis (talk) 16:14, 26 February 2016 (UTC)


 * Of course, colonialism is a corollary of mercantalism: the colonies produce raw materials but do not process it to finished goods. The raw material wealth is extracted from the colonies, and sent back to the mother country for processing.  Wealth is extracted from colonies, but it is added in the mother land.  See Mercantilism which talks explicitly how colonialism and mercantilism worked together.  -- Jayron 32 19:23, 26 February 2016 (UTC)


 * It's not possible to extract raw materials without leaving some wealth in the nation, since infrastructure must be created (roads, railroads, ports, warehouses). Also, it's frequently easier to pay off the theoretical leader of the natives, rather than directly conquering and enslaving them.  But, in cases where the military option is used, you then have to add in military forts to the cost.  And colonial powers also frequently combined a patchwork of kingdoms into larger, more economically viable, nations.


 * On the other hand, the colonial power may well destroy a great deal of the wealth producing ability of a nation, say by preventing the natives from doing their original economic production, like farming or creating crafts, so those workers can be put to work in whatever industry is most profitable to the colonial power. Thus, it's possible that nation may have less economic productivity when the colonial period ends, as the workers may no longer know how to make a living the traditional way. StuRat (talk) 15:56, 27 February 2016 (UTC)


 * Oh, I thought the theory had a formal name or something. Maybe not... 140.254.77.172 (talk) 19:17, 26 February 2016 (UTC)


 * Is imperialism what you're looking for ? --Xuxl (talk) 11:54, 27 February 2016 (UTC)

Two generations born on leap year day
My father said he had heard of both a mother and a daughter both born on leap year day, on February 29. He asked me what are the odds for that. I quickly calculated (1 per 1461) squared, or about 1 per 2.1 million. My father said if it were that common, he'd have heard about it more often. Surely the real world doesn't follow such a nice clean mathematical model. In reality, what probability is there of a parent and their child both being born on leap year day? (Ignore the gender. In the real-world case my father cited, they just happened to both be female.) J I P  &#124; Talk 21:27, 26 February 2016 (UTC)
 * I'd say the real odds are pretty close to what you calculated. Obviously the age difference between parent and child need to be a multiple of four years, but I don't think that makes much of a difference if you average all populations in the world. I appears that slightly fewer people are born per day in February than the overall average (see here), but that will at most result in a 1% difference. Then there's the advanced rules for leap years, according to which leap days actually are about 1 per 1506 days, but that still makes only a 6% difference. I just don't see any reason why the real odds would differ much from your calculation. - Lindert (talk) 21:55, 26 February 2016 (UTC)


 * But, if you specify a living pair, then one would have to be 116 years old, as the last time we skipped leap year was 1900. That is so unlikely we would do better to use the 1/4 chance of a leap year occurring.  StuRat (talk) 15:38, 27 February 2016 (UTC)


 * Likely to get more input and answers at the Math Help Desk. Located here: Reference desk/Mathematics.  Joseph A. Spadaro (talk) 02:16, 27 February 2016 (UTC)


 * No one has posted there yet. Meanwhile, the question must be asked: What is the probability of parent and child having the same birthday, regardless of which calendar date it happens to be? ←Baseball Bugs What's up, Doc? carrots→ 03:48, 27 February 2016 (UTC)


 * Wouldn't that be the same of any two given people regardless of relationship? I share with my uncle but I don't see how it would be different. Mingmingla (talk) 04:24, 27 February 2016 (UTC)


 * Yes, I don't think that the relationship is in any way significant. The probability relates to two people; that is, any two people, regardless of their relationship.  Ignoring leap years (and February 29) for the moment, I believe the probability is 1/365 for the first person to have any specific birthday out of the year; and similarly, 1/365 for the second person to have one specific birthday out of the year.  So, for both people to share the same birthday, the probability is 1/365 * 1/365, which equals 1/133,225.  That's what I believe to be the case.  The leap year simply complicates matters a bit by having us look at the four-year cycle of 1,461 days (instead of simply the one-year cycle of 365 days).   Joseph A. Spadaro (talk) 07:38, 27 February 2016 (UTC)


 * What I'm saying is that there's nothing very special about Feb 29 except that it happens only once every 4 years, in general. The probability of mother and child having the same birthday, for any other day of the year, should be only about 4 times the probability of sharing Feb 29 - and should be the same for all days. ←Baseball Bugs What's up, Doc? carrots→ 09:58, 27 February 2016 (UTC)


 * That would be about 1/16th as much as sharing any specific date, since each must have a birth date that's about 1/4th as common. However, if you don't specify the date, then the chances of any two people having the same birth date is about 1/365.25. StuRat (talk) 15:35, 27 February 2016 (UTC)


 * Mother and child, specifically. The mother is going to have a birthdate, so the child has a 1/365.25 chance of having that same date. So if the mother's birthdate is Feb 29, then the probability of a child having Feb 29 would be 1/1461, right? The OP's question, though, was about a specific date for the mother also. The mother has a 1/365 chance of having any specific birthdate other than Feb 29. And the child has a 1/365 chance of having any specific birthdate other than Feb 29. So as a pair, they have a 1 / (365 x 365) chance of having a shared birthdate other than Feb 29. ←Baseball Bugs What's up, Doc? carrots→ 19:50, 27 February 2016 (UTC)


 * That's a 1/3652 chance of sharing any other specific date, like July 1st. But if you allow for any date, then the chance is 1/365, since the first result must be multiplied by all the possible birthdays they could share.  As for leap day, if you start with the assumption that the mother was born on leap day, then your math is correct, but I see no reason to start with that assumption.  What you found was the chance of a child being born on leap day, GIVEN that the mother was.  So the chances of a mother and child sharing a leap day birth day, given no prior assumptions, is approximately 1/365×42 times the chance that the two share any (unspecified) birth day. StuRat (talk) 20:06, 27 February 2016 (UTC)


 * I think you need to square that second 365, otherwise you're making the probability of both being born on leap day much greater than being born on any other shared date. ←Baseball Bugs What's up, Doc? carrots→ 20:12, 27 February 2016 (UTC)


 * I suppose one thing that would make the odds very slightly less would be the requirement that the mother had to give birth on a day when she was a multiple of four years old. I don't know the demographics - but if (for example) there were significantly fewer births at age 16 than at age 18 (seems reasonable given the laws on age of consent etc) - then the number of years when the woman would be a multiple of four years old, fertile and of an appropriate age could easily be somewhat less than a quarter of the total number of fertile/appopriate years.  It would be hard to adjust for this effect because it depends on birth rates at different maternal ages - but I think it's plausible that it would make this event less likely than your current estimate. SteveBaker (talk) 06:24, 27 February 2016 (UTC)


 * Sort of. But that really has nothing to do with leap years, per se.  That relates to the probability that a female is fertile at, say, age 27; versus the probability at age 28; versus age 29; and so forth.  So, that "changing" demographic (or probability) would exist with every age/year, not just with every "fourth" age/year.  Joseph A. Spadaro (talk) 07:45, 27 February 2016 (UTC)


 * But the point is the since it can only occur on every 4th year of the women's life, her fertility on every 4th year matters for the calculation. So if fertility on her fourth year is above or below average, your calculations based on the assumption it's average won't be right. This and other factors (time of year has already been mentioned above, but also day of the week is likely to be a factor). There's also the interesting question of whether a woman born on February 29, or for that matter in February etc might have a fertility that's different from the average. Particularly if we're talking about someone from a certain area, e.g. the situation in the northern hemisphere Anglosphere or Finland or whatever rather than the worldwide average. I don't think these factors combined are going to make that big a difference, but I wouldn't be completely surprised if it could easily be 10%. (These factors are complicated and to some extent interconnected enough that I don't think we can assume they will balance out.) Nil Einne (talk) 12:05, 27 February 2016 (UTC)


 * Yep. So suppose (to take a 'spherical cow' approach) that women ALWAYS became fertile at age 18 and stopped being fertile instantly at age 30.  In that case there would be 12 fertile years.  If a woman is born on a leap year - then she is only fertile ON A LEAP YEAR at ages 20, 24, and 28.  In that case, she is indeed only likely to be having a baby on a leap year with a 1:4 chance.  But suppose the demographics shift and women became fertile at ages 16 through 32.  Now, there are 16 fertile years - but there are FIVE fertile leap years at ages 16, 20, 24, 28 and 32.  So now the odds of having a leap year baby are 5 in 16...almost one in three.  MUCH more likely than if women were only fertile between ages 18 and 30.   I think that demonstrates clearly that the simplistic math suggested earlier is far from the correct probability.
 * OK - so that's a very contrived case - and all women are different - and probability of giving birth aren't identical in every year of life. But what I'm trying to convey here is that in order to have a leap-year-mother have a leap-year-baby - we're saying that she has to give birth at ages that are a multiple of four - and there specific years aren't equally fertile to non-multiple of four ages.
 * Unfortunately, this makes the math horribly complicated - and demands that you look at the demographics of birth rates at different ages (and indeed, times of year, etc). Since many of those things are culturally determined (in the USA and Europe, we have laws and taboos - and strong efforts to "reduce teen pregnancy" - in other parts of the world, it's not at all rare for very young girls to become pregnant without cultural barriers.  Worse still, cultural norms are shifting - so the probability of mother and child both being leap-babies has changed because of things like birth control and the acceptance of women in the workplace causing some people to choose to have children later in life.
 * So...we know that the naive calculation definitely isn't correct. Without knowing a lot of details about the age, occupation, location of grandmother, and mother - we don't stand a chance of giving you an accurate answer.   The naive answer is probably the best we can come up with for a general estimate - but we know for sure it's not right.  My spherical cow argument kinda inclined to believe that it's on the low side...but if it turned out to be too high, I wouldn't be so surprised. SteveBaker (talk) 20:26, 27 February 2016 (UTC)


 * One other factor is whether a leap day mother would want to try to alter the odds to make a leap day baby more likely or less likely. Guaranteeing a leap day baby would be quite difficult, but trying to get pregnant about 9 months before and then delaying or bringing on delivery early could make it happen.  On the other hand, avoiding a leap day baby is entirely doable.  StuRat (talk) 15:43, 27 February 2016 (UTC)


 * Yes - if leap day-minus-9-months fell on a holiday or a weekend, that might increase the number of people who had intercourse that night - causing a mini-baby-boom on leap day. It's interesting to ask whether mothers would find it amusing or bad news to have a leap-day baby...and there are clear cultural issues about having a child with the same birthday as yours!  Given that parents may have a small degree of control over the birth date (eg if the baby has to be induced) - that could have an impact.  But my gut feel is that this pales into insignificance compared to the demographics of birth rate at different maternal ages.
 * SteveBaker (talk) 20:26, 27 February 2016 (UTC)


 * My Mom was born exactly 9 months after the repeal of Prohibition, so I suspect grandpa and grandma had a little party that night. :-) StuRat (talk) 23:23, 27 February 2016 (UTC)


 * I read THIS on Medium.com today. It says that mothers usually try to avoid having their babies on a leap day - and that births are 7% lower on that day than on other days nearby.  That strongly suggests that (at the very least) 7% of people have sufficient choice about the date of their babies birth to be able to alter it by a day or so.  But I wonder whether that makes a difference?   It reduces the probability of a mother being a leap baby by 7% - but it means that a leap-day mother who enjoyed the weirdness of it through her own life might actually strive to have a leap-day baby instead of trying NOT to have one.  That ought to increase the odds of it happening measurably because we know that there is at least a 7% influence that the parents have on the exact date of their child's birth.  Knowing that at least 7% of parents can, and do, 'adjust' their child's exact birthday by a day or so will definitely skew the odds - but by how much (and in which direction) is hard to tell. SteveBaker (talk) 15:00, 29 February 2016 (UTC)


 * I believe that 7% understates the influence the parents can have, since it includes all those parents who make no attempt to control the birth date, and both those who aim for, and who avoid, leap day. Indeed, if the goal was to avoid leap day, I would expect nearly 100% in developed nations could avoid it by inducing labor the day before, unless this is considered to be medically unethical.  Aiming for leap day would be a bit harder, but a fairly high percentage might still be possible. StuRat (talk) 15:34, 1 March 2016 (UTC)


 * The gestation period is not exactly nine months.  There is considerable variation, which to some extent is due to variation in the lengths of the months themselves. 86.150.228.152 (talk) 20:12, 1 March 2016 (UTC)


 * Yes, as I said, 7% gives us a lower estimate. If every parent tried to adjust the birthdate and if they only attempted to adjust the date AWAY from a leap day - then 7% would be the exact percentage who'd succeed in that goal.  We don't know how many don't try - and we don't know to what extent those who try to adjust towards the leap day are counteracting the ones who adjust to avoid it.  All this number tells us is that AT LEAST 7% are able to adjust the date.  Which tells us that if a leap-day mother actually wanted a leap-day baby, and the baby happened to be coming (let's say) a day later - then her chances of succeeding at changing the date to hit the leap day are AT LEAST 7% - probably much higher - which is clearly a sufficiently significant statistical factor that we'd have to consider it in estimating the odds here.
 * What I find amazing is that there is even a 7% degree of control. I'd expect it to be horribly unethical for medical staff to induce (or somehow delay?) the onset of labor only for a reason like this - but the numbers say it must be true!  SteveBaker (talk) 21:31, 1 March 2016 (UTC)
 * One hears of deliveries being scheduled to fit in with doctors' golfing commitments and the like. Probably apocryphal generally, but maybe there's a germ of truth ....  --   Jack of Oz   [pleasantries]  21:44, 1 March 2016 (UTC)
 * In this country (UK) it's more than a germ.  Maternity wards routinely induce births on Fridays where a weekend delivery is forecast.   It's a fact that if you have a medical emergency at the weekend you're more likely to die.   The government has said it wants to adjust working hours so that the service in hospitals is as good at the weekend as during the week, but the prognosis is not good - junior hospital doctors recently went on strike for the first time ever and more action is planned.
 * There are horror stories about the services provided by locums when the GP's surgery is closed.  Again, the government wants to extend surgery opening hours, but in the dim and distant past GPs (or "family doctors" as they were called) had an evening surgery which any registered patient could attend without an appointment.   Now it can take weeks to get an appointment, people go to A and E (accident and emergency) and the service is collapsing. 86.159.14.122 (talk) 18:44, 2 March 2016 (UTC)