Using SPSS for Windows Part II

1. Using SPSS for WindowsPart II Jie Chen Ph.D. Email: jie.chen@umb.edu Phone: 617 287 5241

2. Table of Contents • Data management • Computing new variables • To sort data • Data selection and split files • Merging files • Statistical procedures • Linear regressions • Regression for aggregated data • Chi-square test for grouped data • Nonparametric tests • Testing Normality

3. Computing New Variables • Open data sample1.sav • To compute a new variable we can • Use a standard formula • Use a statistical function to compute

4. Using a Formula To compute the average income for the past three years for each person: • Click Compute in the Transform menu, • Enter the new variable with the name of “mean” for the target variable Mean = (ptoi92+ptoi93+ptotinc)/3 • Click OK to compute the mean

5. Using a Statistical Function • Click the Compute in the Transform menu • Click the Reset button to clear the old formula • Enter average as the target variable • Locate Mean on function list and move it to the Numeric Expression area (using Up arrow ) • Enter ptoi92, ptoi93 and ptotinc inside the parentheses • Click OK to compute the average

6. Log transformation • Click the Compute in the Transform menu • Click the Reset button to clear the old formula • Enter lnincome as the target variable • Click on Arithmetic in Function group: text box • Locate Ln on functions and Special Variables: list and move it to the Numeric Expression area (using Up arrow ) • Enter ptotinc inside the parentheses • Click OK to compute log of ptotinc.

7. Sorting Data Sorting data involves reordering of data using values of one or more variables. • Sorting data on one variable • Sorting data on more than one variables

8. Sorting Data on One Variable • Click Data/Sort Cases in the Data Editor Window • Click age and move itto the “Sort by:” text box • Click Ascending radio button • Click OK

9. Data Sorted by Age

10. Sorting Data on Two Variables • Click Data/Sort Cases • Click age and move itto the “Sort by:” text box • Click educ and move itto the “Sort by:” text box • Click Ascending radio button • Click OK

11. Data Sorted by Two Variables

12. Three Ways of Data Selection • If condition is satisfied : to select data that meet if conditions • Random sample of cases:randomly chose a specified percentage of cases • Based on time or case range: to select data from a specified range

13. If Condition Is Satisfied To choose data that meet If conditions: • Click the Select Cases in the Data menu • Click the If condition is satisfied radio button • Click If push button to open the Select Cases: If dialog box

14. The If condition If we are interested in the personal total income for females, we need to select the only observations whose sex is female. • Type in sex = 1 in the Select Cases: If dialog box, (1 = “female”) • Click Continue to confirm the rule

15. Two Choices for Unselected Cases • If one clicks the Filtered radio button, the unselected cases remain in the Data Editor, but are not used in analyses. • If one clicks the Deleted radio button the unselected cases are deleted from the Data Editor Window.

16. Complex If conditions Suppose we want to select cases meeting two conditions: region = 1 and age >= 30 • Type in “region = 1 & age>=30” in the Select Cases: If window • Click Continue to confirm the rule

17. The Case Deletion Choice • Switch to the Data Editor Window • Click the Select Cases in the Data menu • Click the Deleted radio button in the Unselected Cases Are: area • Click the OK to delete unselected cases from Data Editor Window

18. The Data Editor Window Containing Only Selected Observations

19. Split File • The data file is split into separate groups for analysis based on the values of a grouping variable • The same analysis is applied to separate subgroups simultaneously • The results for all the subgroups will be presented together

20. To Split a Data file • Open sample2.por • Click the Split File in the Data menu • Click the Organize output by groups radio button • Move sex to the the Groups Based on list box • Click the OK push buttonto Split File

21. Descriptive Statistics Based on Split File • Click Statistics/Summarize/descriptive • Click age in variable list box • Click OK

22. Presenting results by selecting Compare groups

23. Turn Off the Split File Processing • Select Split File in the Data menu • Click Analyze all cases in the Split File dialog box • click OK to set analyses to all cases (turn off split file)

24. Merging Files Data can be combined in two ways • Merging different cases according to the same variables (adding observations) • Merging different variables according to the same cases (adding variables)

25. Merging Cases In the Data Editor Window • Open a data file row1.sav • Click Data/Merge Files/Add Cases, the dialog box of Add cases: Read File is open as shown in the note page • Select file row2.sav and Click open, then the dialog box of Add Cases from... is open • Click OK, the observation from row2.sav are placed in Data Editor Window after row1.sav

26. The Add cases from … dialog box

27. Merging Variables • Open file col1.sav • Click Data/Merge Files/Add Variables. The dialog box Add Variable: Read File shown in the note page will be displayed. • Select file col2.save and Click open. Then the dialog box of Add Variable from... Will appear • Click OK.

28. The Add Variable from … dialog box

29. The Merged File

30. Introduction to Regression • Simple Regression • Multiple Regression • Regression Plots • Regression for aggregated data

31. Simple Regression • Click Analyze/Regression/Linear then the Linear Regression dialog box is open • Use ptotinc (personal total income) as the dependent variable • Use educ as the independent variable • Click OK

32. The Dialog Box of Linear Regression

33. The Output for the Regression

34. The Estimated Regression Equation

35. The Fitted Line

36. Examing the Residual • Click Dialog Recall Tool • Click Linear Regression • Click plots… inthe Linear Regression dialog box • In the Linear Regression: Plots dialog box, chose ZRESID as the Y and ZPRED as the X variables. • Click Histogram • Click Continue • Click Ok

37. The Scatterplot of Residuals

38. Multiple Regression

39. Running a Multiple Regression

40. The Output of Multiple Regression

41. The Fitted Model Y = -13301+ 2672 X1-13106 X2 + 145 X3

42. Residual Plots • Click Plots in Linear Regression Dialog Box • Put ZRESID as the Y variable and ZPRED as the X variable in a scatterplot • Chose Histogram and Normal probability plot in the Standardized Residual Plots

43. Histogram

44. Normal Probability plot

45. To aggregate data • Using Current Population Survey 2006 (CPS2006) data • Click on Data/Aggregate Data • Break Variable(s): • Summaries of Variable(s): • Mean, Median, and Sum • First, Last, Minimum, and Maximum values • To save aggregated variables

46. A random sample from Current Population Survey (CPS2006)

47. The mean and median wages by years of education

48. A regression line of average income

49. A regression line of median income

50. An Example taken from 1982 General Social Survey