Homework Assignments #1-3
All homework assignments must typed or legibly handwritten, and must show your name, the assignment number, course number, and the date clearly. Homework is due at the beginning of class on the specified date.
Homework #1
Due Wednesday, Feb. 14
Indicate which scale of measurement (nominal, ordinal, or interval) each of the following represents. The variable's values or units of measurement are in parentheses.
1. attitude toward gun control (favor, neutral, oppose)
2. number of children in a family (0, 1, 2, etc.)
3. marital status (never married, married, separated, divorced, widowed)
4. frequency of using condoms (never, sometimes, always)
5. height (in whole inches)
6. sex (male, female)
List the highest scale that could be used to measure each of the following variables. Suggest a few possible values or units of measurement.
7. sexual orientation
8. income
9. race/ethnicity
10. highest educational degree obtained
11. A researcher is interested in estimating the average age at marriage for women in New England in the early 18th century. She finds within her state archives reasonably complete marriage records for a large Puritan village for the years 1700-1730. She selects some of these records to examine for her study, noting the age of the bride for each. What is this study's sample? What is the population of interest? Does this coincide with the population to which generalizations can reasonably be made from this study? If no, what is this latter population?
12. Go to the WebStat 2.0 web site (http://www.stat.sc.edu/webstat/version2.0/). Put this site in your browser's bookmarks or favorites so you can return to it quickly in the future. Click on the orange button at the upper right of the screen to start WebStat (it can take a minute or so before this button appears). Go to the "Data" part of the menu and then down to "Sample data sets" and then click on "Billionaires92" (the shorthand for these steps is: Data --> Sample data sets --> Billionaires92). Wait a second or two and then the data should appear in the main part of the screen in rows and columns. Then go to Data --> Show info to get a brief description of the data set and the variables. You can maximize the window to see all the information.
a) What are the units of analysis for this data set?
b) What are the variables included and what scales are they measured on?
c) Answer a) and b) for the "Labor Force" sample data set located in the same submenu as the Billionaires92 data set.
13. Go to the Survey Documentation and Analysis (SDA) web site (http://csa.berkeley.edu:7502/archive.htm). Also put this site in your browser's bookmarks or favorites. Under the "National Omnibus Surveys," click on "GSS Cumulative Datafile 1972-1996." This retrieves information about and data from the General Social Survey, a multistage cluster probability sample survey of adults living in U.S. households. The next screen should read "SDA Demonstration Survey Data Archive." Select the " Browse codebook in this window" option and then hit the "Start" button 2/3 of the way down the screen (not the Windows button with the Microsoft Windows icon) to get information about all of the variables in the data set.
After the next screen appears, click on "Group Headings" on the left side of the screen and then scroll down this outline of question topics until you come to "Societal Concerns." Click on "Confidence in Institutions." The next screen shows a table with the name of confidence in institutions-related variables in the GSS (these variable names will never be longer than 8 characters) and a summary of the question content. Click on the "conjudge" variable. Scroll down just a little on the resulting screen, and look under the "Label" column. These labels are the response options to the survey question.
a) List the response options.
b) Indicate the scale (nominal, ordinal, interval, ratio) with which the CONJUDGE variable was measured and explain your classification.
Using your browser's "Back" button, go back to the "Group Headings" screen with the outline of variables. Go through the outline and find a category that interests you. Select a variable and then:
c) List the name of the variable, the summary of the question, and the response options.
d) Indicate the scale (nominal, ordinal, interval) with which the variable was measured and explain your classification.
Homework #2
Due Wednesday, Feb. 21
Do chapter exercises 2, 4, 6b, 8, and 10 on pp. 61-68.
Then go to the SDA web site and pick one of the data sets to explore (you can use the steps you went through in homework #1 as a guide). Search through the "Group headings" outline of variables for the data set and find a nominal scale variable, an ordinal scale variable, and an interval scale variable. Then go back to the "SDA Demonstration Survey Data Archive" page for that data set. Hit the "Extra Codebook Window" to keep the survey's codebook open in another window. This way you can look up the variables during the exercise if you forgot their names. Minimize the codebook window so you can work in the prior window. Select "Frequencies or crosstabulations" and then hit the "Start" button 2/3 of the way down the screen.
On the next screen, type in the names of the three variables in the Row box. Type the names exactly as they are shown in the codebook, making sure to leave a space between each variable name. Move down the page a little and put a check in the Percentaging section for "column." This means that SDA will not only produce a frequency distribution but a percentage distribution for each of the three variables. Then move down the page a little more to the "Other options" section and put a check for "Question text." SDA will then show the full text of the question for each variable. Finally, hit the "Run the table" button. Print out the results with your browser's print function and then clearly write the scale of measurement for each variable on the output. SDA unfortunately does not produce cumulative frequency/percentage distributions. Compute the cumulative frequency and percentage distributions for the ordinal scale variable by hand or with a calculator, and write them next to the noncumulative distributions.
Homework #3
Due Monday, Feb. 26
A. Do chapter exercise #16 (explain why) on pp. 101-108.
B. Use WebStat to graph the data in exercise 2. You can enter data directly into the WebStat data table (which is like a spreadsheet) by following the directions at http://www.stat.sc.edu/webstat/version2.0/data/Work.html (you can also access this page once you are in WebStat by clicking on the Help section of the menu and then clicking "Using the data table" on the next screen). Load the Billionaires92 data set (see homework #1). For this data set, display each variable's distribution with two different methods that are most appropriate for that variable's scale of measurement. The display tools can be found in the Graphics section of the menu. If you use the histogram option, try using different class widths to see how the picture changes. Print out the graphical results by going to the Options section of the output window (a new window opens for graphical results), and then select Save/Print (hit the "OK" button in the dialog box that pops up). Wait a few seconds for another window to open up with the graphics and then use your browser's print function to print it out. Do this for all of your graphical results and turn them in.
C. Below are data on the marital status of adult women in the U.S. from the Statistical Abstract of the U.S. for 1998.
Marital status Frequency (in thousands)
never married 21,043
married
59,255
widowed
11,027
divorced
11,078
i) What percentage of women were not married in 1998?
ii) Display this information graphically with an appropriate method
(draw graph by hand).