A sociologist interested in the relationship between ...



Practice Questions for the Final Exam

1. The lambda measure of association provides an index of

a. how much we can reduce the error in predicting values of one variable from values of the other

b. how strong the relationship is when we remove the effect of a third variable

c. the significance of a difference between means

d. whether we can generalize a difference between our samples to the entire population

2. In regression analysis, we predict the value of Y from X based on a

a. significant correlation coefficient

b. a mathematical equation

c. a weak positive correlation

d. a normal curve

3. A measure of the proportion of the variance in Y explained by X is known as

a. the coefficient of nondetermination

b. the coefficient of determination

c. the Y-intercept

d. the slope

4. The following students were asked to indicate their college major and their political party affiliation. Calculate the Lambda coefficient and interpret what it means.

Political Party

College Major Democrats Republicans Independents Total

Liberal Arts 45 31 36 112

Business 29 42 35 106

Education 22 10 13 45

Total 96 83 84 263

5. A sociologist interested in the relationship between social class and amount of reading asked a sample of 105 children from varying socioeconomic backgrounds about the number of books they had read outside of school during the last year. For the following data, compute a gamma coefficient to determine the degree of association between socioeconomic status and number of books read. What does the gamma tell you about this relationship?

Socioeconomic Status

Number of Lower Upper

Books Read Lower Middle Middle Upper Total

None 15 12 6 5 38

One 12 8 10 8 38

More than one 4 6 9 10 29

Total 31 26 25 23 105

6. To determine the views of students on a particular campus about fraternities, an 11-point attitude scale was administered to a random sample of 40 students. This survey yielded a sample mean of 6 (the higher the score, the more favorable the view of the fraternities) and a standard deviation of 1.5.

a. Estimate the standard error of the mean

b. Find the 95% confidence interval for the population mean

c. Find the 99% confidence interval for the population mean

7. To estimate the proportion of students on a particular campus who favor a campuswide ban on alcohol, a social researcher interviewed a random sample of 200 students from the college population. She found that 36% of the sample favored banning alcohol. With this information a) find the standard error of the proportion and b) find a 95% confidence interval for the population proportion.

8. Does the number of years that a woman is on birth control have an effect on how long it takes for her to become pregnant once she ceases to use it and tries to have children? A curious researcher collected the following data for a sample of pregnant women who had previously used birth control:

Years of birth control Time until pregnant (in days)

7.5 25

10. 31

5. 42

4. 36

7. 13

5. 22

5. 56

__________________________________________________

a. Draw a scatter plot of the data

b. Calculate the regression slope and Y-intercept

c. Draw the regression line on the scatter plot

d. Can you predict how long it will take for a woman who was on birth control for 8 years to get pregnant once she stops using it?

e. Find the coefficient of determination. What does it mean?

f. Calculate the correlation coefficient (using the correlation formula). What does it tell you?

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