Description
Questions to answer
1. How has per capita income for each decile in the U.S. changed since 1988?
Use the WPID data set to answer this. Give both graphical and numerical results, and
describe in words both the differences in income level between the deciles and the differences
in changes in income for each decile.
2. How does the present distribution of income, relative to a country’s mean, differ
between selected countries?
Use the Ventile data set for the most recent data. For this question, compare the United
States (USA), the United Kingdom (GBR), Germany (DEU), and TWO other countries of
your choice using the most recent available data. We know that (for example) relatively lowincome people in the U.S. have higher incomes than relatively high-income people in Ghana,
so you’ll need to find some way of removing this effect. Find a clear way or ways to graphically
display your results, and briefly write about each country in turn, explain how its distribution
differs (or doesn’t differ) from the others.
3. Is the percentage of income earned by the top 5 percent in a country related to
mean income in that country? What about the percentage of income earned by
the bottom 5 percent? If so, what’s the relationship, and does the relationship have a
simple explanation, such as regional differences? Are there any outliers that require special
explanation?
Again, the Ventile data set has the most recent data.
Write a PDF report of no more than six pages, including graphs, addressing these
questions. The body of the report should not include code — it should be readable to someone
who has never used R (generally you should not just copy-paste output.) Additional graphs for
model checking can be placed in an appendix that does not count toward the six page limit and
which probably no one will read.
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Notes and hints
• There is not necessarily any single objectively right answer to any question in the project.
However, some answers are better than others.
• Whenever you present something that isn’t just raw data, carefully explain what it is and
how it’s calculated.
• Think about whether it’s more appropriate to describe differences in absolute terms or in
percentage terms (or both.)
• You’ll be penalized for any P-value that appears in your report.
What to submit
• A PDF or other file containing your report.
• A .Rmd or other file containing your code.
• Any other supplementary files required to reproduce your work.
Grading
• Question 1: 5 points
• Question 2: 5 points
• Question 3: 10 points
• Communication: 10 points. Full credit for presentation requires a readable, informative,
comprehensive, clearly labeled set of graphs, and a comprehensible write-up with few glaring
spelling and grammatical errors that makes the main points of the analysis clear.
3