Using SPSS for Windows Part II Jie Chen Ph.D. Phone: /6/20151

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 10/6/20152

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

10/6/20154 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

10/6/20155 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

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.

10/6/20157 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

10/6/20158 Sorting Data on One Variable Click Data/Sort Cases in the Data Editor Window Click age and move it to the “Sort by:” text box Click Ascending radio button Click OK

10/6/20159 Data Sorted by Age

10/6/ Sorting Data on Two Variables Click Data/Sort Cases Click age and move it to the “Sort by:” text box Click educ and move it to the “Sort by:” text box Click Ascending radio button Click OK

10/6/ Data Sorted by Two Variables

10/6/ 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

10/6/ 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

10/6/ 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

10/6/ 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.

10/6/ 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

10/6/ 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

10/6/ The Data Editor Window Containing Only Selected Observations

10/6/ 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

10/6/ 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 button to Split File

10/6/ Descriptive Statistics Based on Split File Click Statistics/Summarize/descriptive Click age in variable list box Click OK

10/6/ Presenting results by selecting Compare groups

10/6/ 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)

10/6/ 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)

10/6/ 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

10/6/ The Add cases from … dialog box

10/6/ 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.

10/6/ The Add Variable from … dialog box

10/6/ The Merged File

10/6/ Introduction to Regression Simple Regression Multiple Regression Regression Plots Regression for aggregated data

10/6/ 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

10/6/ The Dialog Box of Linear Regression

10/6/ The Output for the Regression

10/6/ The Estimated Regression Equation

10/6/ The Fitted Line

10/6/ Examing the Residual Click Dialog Recall Tool Click Linear Regression Click plots… in the 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

10/6/ The Scatterplot of Residuals

10/6/ Multiple Regression

10/6/ Running a Multiple Regression

10/6/ The Output of Multiple Regression

10/6/ The Fitted Model Y = X X X3

10/6/ 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

10/6/ Histogram

10/6/ Normal Probability plot

10/6/ 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

10/6/ A random sample from Current Population Survey (CPS2006)

10/6/ The mean and median wages by years of education

10/6/ A regression line of average income

10/6/ A regression line of median income

10/6/ An Example taken from 1982 General Social Survey

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10/6/ Death Penalty Data in SPSS

10/6/ Crosstabulation with Row Percentage

10/6/ Comparison of Row Percentages

10/6/ Repeated Measures Analysis Repeated measures analysis of variance involves testing for significant differences in mean when the observation appears in multiple levels of a factor.

10/6/ Opening the data Click File/Open in the Data Editor Window Click SPSS (*.sav) choice on the File of type pull-down list Look in Floppy (A) and click blood in the file list Click Open

10/6/ Opening the Repeated Measures Dialog Box Click Analyze/General Linear Model/Repeated Measures Replace factor1 with time in the Within- Subject Factor Name text box Press Tab key to move to the number of levels text box and type 3 Click Add push-button and then click Define push-button

10/6/ Click and drag from time1 to time3 Click right arrow to move time1 to time3 into the Within-Subject Variables box Click gender and move it to the Between- Subjects Factor box Click OK push button

10/6/ Examining the results

10/6/ Compare the Main Effects Click Dialog Recall Tool Click Define Push-button Click Options push-button Move time into the Display Means for list box Click Compare Main Effects checkbox Click Continue to process the request Click Ok

10/6/ Pairwise Comparisons

Testing the Normality To test if Age variable is normal distributed. Using file: sam1000.sav Using both graphs and tests Click on Analyze/Descriptive Statistics/Explore… – To chose Age variable in the dependent list – Click on Plots push button. – Check Normality plots with tests. 10/6/201562