# Examination 2

Directions:
You should write the exam in your word processor and copy/paste the answers into the form once you are finished. Do not submit the exam in parts. Rather, submit the entire exam before the deadline. I will only grade the last version you send.

Respond to each item in a clear and concise paragraph. (In some cases, a single sentence will suffice.) Do not copy passages from the lectures or book. Rather, express your own understanding of the material. Do not write anything or everything that comes to mind; instead, try to devise a brief answer that captures the most relevant information. Before you submit, make a note of the number in the first comment, below. You will need to input this number into the form to submit your work. (This is to prevent spammers from using the form. Sorry about that. Spammers ruin everything.) After you submit, you will be returned to the schedule page.

Part I. Probability
Use the following code to produce a crosstabulation. From this table, calculate the following probabilities:
(You can run this script by typing at the prompt: `source("http://www.bcsociology.org/online/files/SOCY7112exam2.r")`

``` library(gmodels) CILS<-read.csv("http://www.bcsociology.org/online/files/CILS2010.csv") attach(CILS) CrossTable(V43,V23,prop.r=F,prop.c=T,prop.t=F,prop.chisq=F,chisq=F,fisher=F)```

1. What is the probability that a respondent selected at random is not a US citizen?

2. How much more or less likely is a US citizen to be much better off compared to non-citizens?

3. Are non-citizens more likely to be better off (better/much better) or worse off (worse/much worse)?

Part II. Standard Scores
Suppose you have a population of 1,200 city agencies. The mean budget for these agencies is \$12.87 million. The standard deviation is \$21.9 million.

4. What is the likelihood that you could select a city agency at random that had a budget greater than \$35.5 million?

5. What is the likelihood that you could select a city agency at random that had a budget below \$10 million?

6. What is the likelihood that you could select a city agency at random that had a budget between \$33.3 million and \$36 million?

Part III. The Sampling Distribution

7. What are the three important characteristics of the normal curve? Why are these signficant?

8. Why is the standard error of the sampling distribution always smaller than the standard deviation of the population?

Suppose that you have a population of campaign speeches from the 1980s. The mean number of references to "family values" in a speech is 6.73, with a standard deviation of 14.4.

9. What is the probability of drawing a random sample of 300 speeches with a mean between 5 and 6 references?

10. What is the probability of drawing a random sample of 100 speeches with a mean of 8 or more references?

Part IV. Data Analysis

11. Select a variable from CILS. Calculate a 95% confidence interval and interpret the results.

12. Select two binary variables from CILS. (You may recode one or both categorical variables into a binary.) Calculate the crosstabulation with odds and interpret the results.

13. Select a categorical variable and a numeric variable from ANES 2012 and perform the hypothesis test. Interpret the results.

14. Select two categorical variables and one numeric variable from ANES 2012 and perform the hypothesis test. Interpret the results.

Part V. Articles

15. Summarize Table 1 in Stockard and O'Brien.

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