# New Version of Exam 3

Here are the revised questions. You can submit the document to me at dr.timothy@shortell.nyc (Word, Pages, OpenOffice, or PDF are fine).

1. What is latent structure and and how do PCA, MDS, or k-means clustering reveal it?

2. Compute PCA in R on a subset of the feeling thermometer variables that appear in both the 2012 and 2016 ANES surveys. Compare the results from the two time points. What can you say about the American political imagination?

3. Using the same subsets as in (2), compute k-means clustering analysis in R and interpret the results. How does the interpretation compare to that for PCA?

4. Using the concept co-occurrence data frame, compute MDS in R and interpret the results.

5. Describe the data and methods used in the Shortell article.

6. Summarize the results shown in Table 1 of Shortell.

7. Summarize the results shown in Table 1 in Swedlow & Wickoff.

8. Summarize Figure 2 in Cappell & Guterbach