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POLS 508 Student Assessment
Name: _________________________________
POLS 508 Student Assessment
Question 1: You expect that there is a relationship between the number of US troops deployed in a
country and how much that country spends on its own defense as a ratio to its Gross Domestic Product
(GDP). The term for this ratio is defense burden (Defense/GDP). You expect that, on average, a country
that hosts US troops will have less incentive to fund its own defense expenditures because it will have
part of its security covered by the United States.
(1) Write a testable hypothesis that conforms to these expectations.
(2) Write an appropriate null hypothesis for your hypothesis.
Question 2: Using Question 1, draw a graph that displays the independent and dependent variables on
their appropriate axes and demonstrates the expected theoretical relationship between the two
variables from your hypothesis in Question 1.
POLS 508 Student Assessment
Question 3: What unit of analysis would you use for question 1?
Question 4: What type of variable is defense burden? What type of variable is “the number of troops?”
Question 5: Using the number series (7, 2, 7, 3, 7, 5, 7, 11, 3, 11, 4, 11, 5, 11, 1, 11, 13, 17), calculate the
mean, median, mode, variance, and standard deviation.
POLS 508 Student Assessment
Question 6: Using the number series (7, 2, 7, 3, 7, 5, 7, 11, 13, 17), calculate the mean, standard error of
the sample mean, degrees of freedom, and a 95% confidence interval of the sample mean.
POLS 508 Student Assessment
Question 7: Using the following data, calculate the Pearson’s r coefficient
State
California
Texas
New York
Florida
GDP (billions of 2015 US Dollars)
2.42
1.65
1.44
.883
Question 8: Interpret the value you calculated in Question 7.
Homicide Rates (2014)
4.4
4.4
3.1
5.8
POLS 508 Student Assessment
Question 9: Using the following data, calculate a regression equation using GDP to predict homicide
rates.
State
California
Texas
New York
Florida
GDP (billions of 2015 US Dollars)
2.42
1.65
1.44
.883
Homicide Rates (2014)
4.4
4.4
3.1
5.8
Question 10: Assume you calculated a regression from Question 1 to see if more US troops in a country
decreases the defense burden of that country. You received a coefficient of -.07 and a standard error of
.0411. Using a one-tailed test, is this result statistically different from 0?
POLS 508 Student Assessment
Question 11: To the best of your ability, interpret column (3) of the following table. The dependent
variable is the percent of questions correct on a multiple choice exam. Spring is a dummy variable that
takes on the value 1 if the student was in the Spring of 2014 or a 0 for Fall 2013. Gender is 1 for female,
0 for male. Standing is an ordinal measure of a students status (1st, 2nd, 3rd, or 4th+ year). The Quiz
variables measures the students quiz performance prior to an exam.
POLS 508 Student Assessment
Question 12: What issues might I have if I expect there to be heteroscedasticity in the model from
Question 11?
Question 13: In model 3, imagine that performance on Exam 1 and performance on the quiz before
Exam 1 are correlated at r = .87. Looking at your regression output, someone says “Clearly, only
performance on Exam 1 predicts performance on other exams. Performance on the quiz before exam 1
has no correlation to performance on later exams.” Using what you know about regression assumptions,
explain a flaw with this statement.
POLS 508 Student Assessment
Question 14: Using column 1 of question 11, predict what score a Junior, male student in Spring 2014
who scored an 88 on the first quiz would make on the exam.