Download Homework 7: Three Interval Tests

SOC497: Sociological Research Methods
@ CSUN w/ Ellis Godard
Homework 7: Three Interval Tests
Comments: You’ve used crosstabs in lab and homework assignments to examine nominal and ordinal relationships. But f
if either of the variables (dependent or independent) is interval, crosstabs won’t work – partly because the size of the table
makes it difficult to summarize, as you saw in the output for homework 5.
Instructions: For this assignment, you will be using the data file 3Tests.sav to examine variation in respondents’ number
of years of education completed (the dependent variable). The dataset includes six variables, including five which can be
used to assess possible explanations for variation in education (i.e. five possible independent variables):
•
SEX has two categories, so you can simply analyze their difference in means (using a “t-test)
•
RACE and REGION both have more than two categories, so require ANOVA procedures (“F tests”)
• AGEWED and AGE are interval, so require regression analysis (tests using “r”)
Conduct those five statistical tests, and use the results to answer the questions below. Be specific and creative!
Submit answers on this sheet as well as relevant output from SPSS. (Clean it up before you print it!)
1. What is the average number of years of education completed for…
a. Male respondents?
___________
b. Female respondents?
___________
c. White respondents?
___________
d. Black respondents?
___________
e. Respondents in the South?
___________
f. Respondents in the West?
___________
g. Respondents who are 25?
___________
h. Respondents who married at 20? ___________
2. Briefly summarize those results using the comparisons provided by all five variables. What types of respondents
have the most education? (Warning: You’ve only looked at this independent variables one at a time; do not
discuss joint effects as if you’ve looked at respondents are are, for example, black and female; you haven’t!
However, you could describe a hypothetical “ideal type” respondent using all five variables.)
3. What are the probability values associated with these potential explanatory variables:
a. SEX
____________
b. RACE
____________
c. REGION
____________
d. AGEWED
____________
e. AGE
____________
4. Briefly summarize those results – for which of these fives “causes” can we be comfortable generalizing our results
beyond the sample, to the population at large?
5. What are the r-squared values associated with the two regression tests?
a. AGEWED
____________
b. AGE
____________
6. Briefly summarize those results, including the test statistics and the significance levels associated with each, and
assess them relative to each other.
7. BONUS: Give three interpretations of each r-squared value (strength, explained variance, and reduction in error).