Questions
1. Causal Inference [15 points]
Many microfinance programs are introduced in a staggered
manner. That is, one group of locations
get the program today, another gets the program in 6
months, and so on. Suppose you are asked by
your country’s government to evaluate the impact on
poverty of a microfinance scheme that was
provided to region A in January 2000, region B in July
2000, region C in January 2001, and region
D in June 2001. Suppose that (i) you have data on poverty
rates in all four regions in January of
each year 1999-2002, and (ii) if microfinance has any
impact on poverty, it will occur within 6
months.
(a) Describe a difference-in-difference procedure to
estimate the impact of microfinance on
poverty rates. What will you measure? When? What will the
treatment group(s) and control
group(s) be?
(b) Suppose that in January 2000, households in regions
B, C and D were notified that they
would not receive the program until the later scheduled
date. As a result, these households
began to work even harder and earn more income than
before they learned about the
forthcoming program. This is an example of what type of
bias/effect? Will this effect lead
you to over- or under-estimate the true impact of
microfinance access on poverty? What
would be one solution for addressing this bias?
(c) Suppose that region A is poorer than region B, which
is poorer than region C, which is
poorer than region D. This suggests that policymakers
chose to place the program in poorer
regions first. This is an example of endogenous program
placement, which can bias our
estimates of program impact. Suppose that you can go back
in time and design a randomized
control trial (RCT) to study the impact of microfinance.
How would the design compare to
the approach in part (a)?
(d) Suppose that region B is adjacent to region A and
some households in region B gain access
to the program as early as January 2000. This is an
example of what type of problem in
program evaluation? How will this affect the estimated
impact of the program if we just
focused on the difference-in-difference estimate for
regions A and B? [Hint: how will YB1–
YB0 look in this case compared to a case where region B is
very far from region A and no
households in B receive the program until July 2000?]
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(e) Suppose that it is now the year 2005, the program
exists in every region, and you are
interested in study the impact of microfinance on
business creation. Someone notices that
the microfinance institutions in region B only provide
credit offers to households with
landholdings less than 0.5 hectares. How would you use
this rule to estimate the program
impact? Describe the empirical strategy: define the
treatment and control groups, state the
relevant assumptions, etc.
2. Ethnic Diversity, Conflict, and Income [10 points]
(a) Suppose there are three ethnic groups in country C:
group 1 has 30 people, group 2 has 10
people, and group 3 has 50 people. What is the degree of
ethnic fractionalization? Now
suppose country C splits into two countries where country
C1 has 10 people from
group 1,
10 people from group 2, and 10 people from group 3.
Country C2 has the remaining
population. Did the splitting create more or less
fractionalized countries compared to the
original country C? From the perspective of the Esteban
and Ray model, which country (C1
or C2) will have more conflict in equilibrium?
(b) What is the degree of ethnic fractionalization in
your country? Discuss one way that
fractionalization might (indirectly) affect economic
growth in the Solow model?
(c) Suppose you are interested in understanding the
effects of income on conflict. Some
researchers argue that commodity price shocks are a good
instrumental variable for income.
Others (like your professor) argue that price shocks are
not a good instrument. Explain what
assumptions are required for price shocks to be a good
instrument in this context and why
these assumptions may not hold.
(d) Briefly note any major conflict episodes in your
country since 1990. Report the number of
battle deaths since 1990 as recorded in the WDI.
(e) What effect might conflict have on economic growth?
Explain through the lens of the Solow
model supposing that the country is below its steady
state before the conflict. Make a
distinction between short-term and long-term effects
focusing on the potential impacts on
the following variables: savings, population, capital,
and technology.
3. Demographic Transition [10 points]
(a) Construct a demographic transition plot for your
country with the birth rate, death rate, and
population level all on the same graph over the period
1960—2010 (there may be missing
data; connect points using straight line; put population
on the right Y axis and birth/death
rates on the left Y axis). Discuss (i) the historical
patterns, and (ii) potential implications for
economic growth in the next decade.
(b) Now, construct a graph showing the birth rate and the
infant mortality rate. Describe the
patterns and offer a potential explanation for the
relationship.
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4. Population and Fertility Choice
4.1. True or False? [6 points]
State whether the statement is true or false [2 points],
and briefly explain why [1 point]
(a) The populations of Europe and North America grew at a
combined rate between 1650 and
1930 that significantly exceeded the population growth
rates of developing countries at that
time.
(b) If country A has a population growth rate that is
lower than country B, then the average
woman in country A has fewer children than her
counterpart in country B.
(c) Total population levels in a country should be lower
at the end of a demographic transition
than they were at the beginning.
4.2. This is a question on joint families, externalities,
and fertility choice. Suppose that Jose
and Maria are the heads of a nuclear family, making their
fertility decisions. For simplicity,
suppose there is no gender bias and no infant or child
mortality. The following table details
the costs and benefits (in dollars, say) of different
numbers of children. [6 points]
(a) Based on the information in the table, how many
children would Jose and Maria have in
order to maximize their net benefit?
# of children Total benefit ($) Additional cost per
additional child ($)
One 500 100
Two 750 100
Three 840 100
Four 890 100
Five 930 100
Six 950 100
Seven 960 100
Eight 960 100
(b) Now consider two identical nuclear families: Jose and
Maria (as above), and Jorge and
Rosa. Jose and Jorge are brothers and the two couples form
a joint family. Both couples
have exactly the same costs and benefits of having
children as in the table. Now suppose that
50% of the upbringing costs of each child (e.g., child
care) can be passed on to the other
family. Each couple makes independent decisions, taking
only its own welfare into account.
Now how many children will each couple have?
(c) Explain the reason for this seemingly paradoxical
result, using the concept of externalities,
and try to understand why larger families (either
integrated across generations or between
siblings in the
same generation) will tend to have a larger number of children per couple.
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