Assignment #3

PPol 603

Due: Thursday, 20 September 2012, 9:30 a.m.

Type up your answers. Read the section in the syllabus on Academic Honesty and Plagiarism (here) to make sure you are giving proper credit to those you work with and/or the text(s).

Solve the following problems. Show all of your work, but keep your answers concise. Highlight your (final) answer to distinguish it from your other numbers and text. Include a copy of your input (e.g. do file) or output (e.g. log file), when it is an appropriate way to show your work. However, do not include unnecessary output (i.e. no data dumps), and format any output so that it is easily readable. An appropriate time to include output is when you put your results in a table--if your results are wrong, then graders have no idea how you came to your conclusions (i.e. give partial credit) unless you provide some output. Explanation includes statistical and substantive explanation (explain so that a statistical layperson can understand it, and so that a statistical analyst will see your erudition).

1. {18 points} Do Problem 3.5, parts b., c., and d. in Stock and Watson.
2. {16} [from Agresti and Finlay 2009] According to a union agreement, the mean income for all senior-level assembly-line workers in a large company equals $500 per week. A representative of a women's group decides to analyze whether the mean income for female employees matches this norm. For a random sample of nine female employees, y-bar = $410 and s = 90.
   a. Conduct a hypothesis test of whether the mean income of female employees differs from $500 per week. Include all assumptions, the hypotheses, test statistic, and p-value, and interpret the result. If you need to make an assumption to conduct a test, state the assumption, and conduct the test.
   b. Give the 95% confidence interval for the mean income of female employees.
   c. Do these data suggest that the company is guilty of gender discrimination in its compensation policies? Explain.
3. {21} Do Problem 3.16 in Stock and Watson.
   • In part b., use both a hypothesis test and the confidence interval (from part a.) to answer the question. Discuss how the hypothesis test and confidence interval are related or not.
   • In part c., change the problem so that the average test score after the course is 1025 (not 1019), keeping the standard deviation and sample size the same.
   • In part c.ii., use both a hypothesis test and the confidence interval (from part c.i.) to answer the question. Discuss how the hypothesis test and confidence interval are related or not.
   • In part d.ii., why do the statistical conclusions differ (or not) in part c. and d. given they are both about change in average test scores, considering the different changes and sample sizes?
4. {20} Do Problem E13.1, parts a. and d. in Stock and Watson. [NOTE: The first Empirical Exercise in Chapter 13.]
   • For part d., use experience and employment holes to examine possible non-random assignment.
   • Some employers claim to be "equal opportunity employers" (eoe). Do these businesses appear to respond to black applicants at higher rates than employers who do not claim to be equal opportunity employers?
   • Suppose in previous studies of call-backs, the average call-back rate was 0.1. Test whether the call-back rate for whites is equal to (i.e. statistically different than) 0.1. What do we conclude?
5. {25} Research Project Proposal:
   Turn in a one-page, double-spaced proposal (standard font and margins) outlining the public policy research question you plan to address, explains a potential causal connection linking an independent and dependent variable, offers at least 4 relevant citations, and discusses possible data sources to be used. The dependent variable must be at least roughly continuous.

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