Some people wonder why there are more "sisters and one brother" in rural areas, but the total number of women is less than that of men. Because if there are many sisters in the family, just to give birth to a younger brother is a common phenomenon, then there should be more women than men?
There is a master who has built a mold, which is very strong, and shares it as follows:
This question is well explained, and it is called "disappearing women" in economics. The subject thinks so.
A family, give birth to a child, boy! Come to an end!
B family, give birth to a girl, continue; Regenerate a girl, go on; Regenerate a girl, go on; Give birth to a boy and it's over!
So there should be 3 women and 2 men in this village, right?
In fact, in terms of statistical probability, the probability of having a boy or a girl is basically close to 50%. In other words, half of the families in this village have born boys and half have girls, and the ratio of men to women should be 1:1. The families that gave birth to boys all raised these boys, and the families who gave birth to girls chose to raise the girl, and the families who gave birth to the girls chose to abandon the baby, sell it, and so on, and then give birth again.
And then there are half males, half females, and then those who give birth to girls choose to raise girls, continue to give birth, and choose to abandon babies...And so on and so forth.
So let's make three simple assumptions, 1. This cycle only goes on twice, that is, if you give birth to two children, you are not allowed to give birth, even if you abandon the girl (real life is crueler than this, because the abandoned baby can be reborn later).
2. There are 100 families in this village.
3. A = 50, i.e. a% = 50%.
Phase 1: 50 households gave birth to sons and 50 families gave birth to daughters. Fifty families with boys chose to stop having children.
25 out of 50 families with daughters chose to raise their daughters but continued to give birth; Twenty-five households chose to abandon the baby.
Phase 2: 25 households gave birth to boys and stopped giving birth.
12.5 households (about 13 households) gave birth to daughters and chose to raise them. 12 families chose abandoned babies.
So, how many boys are there in this village now?
50 in the first phase and 25 in the second phase, for a total of 75 boys.
How many girls are there?
Twenty-five survived in the first phase and 13 in the second phase, for a total of 38 girls.
As a result, the ratio of men to women in this village is 75:38.
In addition, there will be 50 households with only children (male), 25 households with sisters and younger brothers, 13 households with two daughters, and 12 households without children.
So there is the question of the subject.
Hey? You see, it is the elder sister with the younger brother, and there is no elder brother with the younger sister, which means that as long as the girl is born, the boy will continue to be born. So why is the male-to-female ratio 75:38 in the end?
Because, there are a lot of women who have "disappeared"!
It's brutal, and, weird!
Disappearing her ...
Of course, the above is a theoretical analysis, but in fact, especially in the ** decade, in many cities, the skew of resources in the process of parenting led to an increase in the rate of premature death of girls, such as beach incidents, ignoring the safety of girls or consciously putting girls in danger, in the case of serious illness, families will do their best to save boys, and girls may be abandoned** and so on.