Problem Set 1 Answer Key
Statistical Methods for Development Policy
Prof. Franck Wiebe
Due: September 19, 5:00 pm
Please show all of your work and explain any qualitative answers for full credit. Remember if you choo
...
Problem Set 1 Answer Key
Statistical Methods for Development Policy
Prof. Franck Wiebe
Due: September 19, 5:00 pm
Please show all of your work and explain any qualitative answers for full credit. Remember if you choose
to work with a partner you should both submit your own copy of problem set and follow the instructions
for working with others as outlined in the syllabus. Be sure to turn in a neat, stapled problem set to your
TA’s mailbox in the hallway just outside the Old North Student Lounge.
If you worked on this problem set with another classmate, please provide their name: _______________
TOTAL POINTS: 50
1. A group of International Development policy makers wants to know how many households are
food insecure in a developing country. Because the government of this country is reluctant to
provide them with reliable data, this group of policy makers relies on regional data collected by
independent prestigious NGOs. This is what they have collected so far:
Region % Food insecure households by region
Norte Grande 27%
Nuevo Cuyo 26%
Centro 25%
Patagónica 28%
Is the following statement true or false? “For the country as a whole, the percentage of food
insecure household must be less than 29%.” Explain your answer using a numerical example.
(2 points)
In an extreme case, assume that ‘Patagónica’ has the 99.97% of the total population in the
country and the rest of the regions has 0.01% each one.
Hence, the percentage of food insecure households in the whole country is:
food insecure=27 (0.001)+26 (0.001)+25 (0.001)+28 (0.997 )=27.994
Note that 27.994% < 29%
If we decreased the share of population in ‘Patagónica’, the total percentage of food
insecure households in the whole country would decrease as well:
food insecure=27 (0.01)+26 (0.01)+25 (0.01)+28 (0.97 )=27.94
Note that 27.94% < 27.994% < 29%
Therefore, the statement is true. However, it does not explicitly say that there are
only four regions in the country. If there were more regions, then it’s possible to
come up with a percentage greater than 29%.
12. A university implemented a survey to know which devices students are using when they work on
their policy memos. This university was particularly interested in the use of the following three
devices: desktops, laptops and tablets. These are some of the results of the survey:
Ten students use desktops
25 students use tablets
60 students use laptops
Ten students use both laptops and tablets
Four students use both tablets and desktops
Four students don't use any of the three devices
70 students don't use desktops
Two students use the three devices (laptops, tablets and desktops)
Please, answer the following questions:
i. How many students use only desktops? 1 (1 point)
ii. How many students use at least one device? 76 (1 point)
iii. How many students were surveyed? 80 (2 points)
Reference the Venn Diagram below:
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