**Class 3: Births and Gender**

**Part 1: Family planning**

Suppose that a
certain society values sons more than daughters. In this society, a couple will
continue bearing children until they produce a son, at which point they will
retire from the child-bearing business.

- Would this
family-planning scheme tend to produce more boys, or more girls?
- Using coin tosses,
simulate the generation of twenty families. Make histograms for the number
of sons and the number of daughters. Find the percentage of boy babies and
girl babies in your simulation. In light of this data, are you inclined to
change your answer to the previous question?

**Part 2: Gender bias in
births**

Read the first part of the
article ÒU.S. Births Hint at Bias for Boys in Some AsiansÓ.

The article states, ÒIn general,
more boys than girls are born in the United States, by a ratio of 1.05 to
1. But among American families of
Chinese, Korean, and Indian descent, the likelihood of having a boy increased
to 1.17 to 1 if the first child was a girl É if the first two children were
girls, the ratio for a third child was 1.51 to 1 É in favor of boys.Ó

1.
What does it
mean that the ratio of boys to girls for the third child was 1.51 to 1 in favor
of boys, when the first to children were girls?

2.
Suppose you flip
a coin and it lands heads twice in a row.
If you flip it a third time, what is the chance that it lands heads
again?

3.
Why do you think
that the ratio for the third child is 1.51 to 1 and not 1 to 1 or 1.05 to
1?

4.
The article goes
on to say that Ò É in China É the governmentÕs one-child policy has resulted in
the worldÕs highest sex disparity among newborns – about 120 boys born
for every 100 girlsÓ, and ÒIn China, sex selection is usually achieved by
aborting female fetuses.Ó Estimate
the fraction or percent of female fetuses that are aborted in China.

**Journal Assignment: **

Finish reading the article
ÒU.S. Births Hint at Bias for Boys in Some AsiansÓ and comment.

1) If couples could magically determine the sex of their
offspring, what would happen? Would there be a sudden increase in the number of
boys, or girls? If so, would this imbalance correct itself?

2) If society were able to prevent the use of this magical
method, would it have the right to do so? If so, would it be well-advised to do
so?

**Homework Assignment 3 for
Tuesday, Sept. 8: **

Do review exercises 2,4,7,10
in Ch 3. Read Ch 4 and do review
exercise 1, 3 in Ch 4.

**By Sunday, complete and submit the questionnaire
posted on Blackboard.**