Week 7 Linear Regression Exercises

Simple Regression

Research Question: Does the number of hours worked per week (workweek) predict family income (income)?

Using Polit2SetA data set, run a simple regression using Family Income (income) as the outcome variable (Y) and Number of Hours Worked per Week (workweek) as the independent variable (X). When conducting any regression analysis, the dependent (outcome) variables is always (Y) and is placed on the y-axis, and the independent (predictor) variable is always (X) and is placed on the x-axis.

Follow these steps when using SPSS:

1.    Open Polit2SetA data set.

2.    Click on Analyze, then click on Regression, then Linear.

3.    Move the dependent variable (income) in the box labeled "Dependent" by clicking the arrow button. The dependent variable is a continuous variable.

4.    Move the independent variable (workweek) into the box labeled "Independent."  

5.    Click on the Statistics button (right side of box) and click on Descriptives, Estimates, Confidence Interval (should be 95%), and Model Fit, then click on Continue.

6.    Click on OK.

Assignment: Through analysis of the SPSS output, answer the following questions.

1.    What is the total sample size?

2.    What is the mean income and mean number of hours worked?

3.    What is the correlation coefficient between the outcome and predictor variables? Is it significant? How would you describe the strength and direction of the relationship?

4.    What it the value of R squared (coefficient of determination)? Interpret the value.

5.    Interpret the standard error of the estimate? What information does this value provide to the researcher?

6.    The model fit is determined by the ANOVA table results (F statistic = 37.226, 1,376 degrees of freedom, and the p value is .001). Based on these results, does the model fit the data? Briefly explain. (Hint: A significant finding indicates good model fit.)

7.    Based on the coefficients, what is the value of the y-intercept (point at which the line of best fit crosses the y-axis)?

8.    Based on the output, write out the regression equation for predicting family income.

9.    Using the regression equation, what is the predicted monthly family income for women working 35 hours per week?

10. Using the regression equation, what is the predicted monthly family income for women working 20 hours per week?