1. © Copyright 2000, Julia Hartman 1 An Interactive Tutorial for SPSS 10.0 for Windows © Analysis of Covariance (Regression Approach) by Julia Hartman Next

2. © Copyright 2000, Julia Hartman 2 ANCOVA (Regression Approach): Introduction Analysis of Covariance (ANCOVA) is used: To assess the joint significance of predictors on a continuous outcome (GLM approach) To generate prediction equations for various levels of a categorical predictor (regression approach) Next

3. © Copyright 2000, Julia Hartman 3 ANCOVA (Regression Approach): Introduction This tutorial uses the regression approach to ANCOVA to determine if type of undergraduate major and year of matriculation can be used to predict MCAT scores. Next

4. © Copyright 2000, Julia Hartman 4 Dependent variable  nmtot1: MCAT total, 1992-present, most recent) Independent variables  matyr: Year of matriculation  Indicator (dummy) variables computed for undergraduate major  dmajor1  dmajor2 Next ANCOVA (Regression Approach): Introduction

5. © Copyright 2000, Julia Hartman 5 To correctly use the regression approach to ANCOVA requires computing indicator (dummy) variables for different values of categorical variables. Next ANCOVA (Regression Approach): Introduction Variables can be computed by using: Transform procedure (see Computing Variables tutorial)Computing Variables SPSS syntax (see Using Command Syntax tutorial)Using Command Syntax

6. © Copyright 2000, Julia Hartman 6 This tutorial uses the dummy variables shown below to represent the three types of undergraduate majors. Next ANCOVA (Regression Approach): Introduction Type of Major Value of dmajor1 Value of dmajor2 Biology/Chemistry10 Other science, health01 Other (non-science)00

7. © Copyright 2000, Julia Hartman 7 ANCOVA (Regression Approach): Starting the Procedure In the menu, click Analyze

8. © Copyright 2000, Julia Hartman 8 ANCOVA (Regression Approach): Starting the Procedure In the menu, click on Analyze Point to Regression

9. © Copyright 2000, Julia Hartman 9 ANCOVA (Regression Approach): Starting the Procedure In the menu, click on Analyze Point to Regression Point to Linear…

10. © Copyright 2000, Julia Hartman 10 ANCOVA (Regression Approach): Starting the Procedure In the menu, click on Analyze … and click. Point to Regression Point to Linear…

11. © Copyright 2000, Julia Hartman 11 ANCOVA (Regression Approach): Selecting Variables Choose the variables for analysis from the list in the variable box. Move MATRICULATON DATE - YEAR, which is already highlighted, to the box labeled Independent(s) by clicking the arrow.

12. © Copyright 2000, Julia Hartman 12 ANCOVA (Regression Approach): Selecting Variables Scroll down the variable list,

13. © Copyright 2000, Julia Hartman 13 ANCOVA (Regression Approach): Selecting Variables Scroll down the variable list, point to the variable labeled MCAT TOTAL 1992- PRESENT, MOST RECENT [nmtot1]

14. © Copyright 2000, Julia Hartman 14 ANCOVA (Regression Approach): Selecting Variables …and click. Scroll down the variable list, point to the variable labeled MCAT TOTAL 1992- PRESENT, MOST RECENT [nmtot1]

15. © Copyright 2000, Julia Hartman 15 ANCOVA (Regression Approach): Selecting Variables Move nmtot1 to the Dependent box by clicking the arrow.

16. © Copyright 2000, Julia Hartman 16 ANCOVA (Regression Approach): Selecting Variables Scroll to the bottom of the list,

17. © Copyright 2000, Julia Hartman 17 ANCOVA (Regression Approach): Selecting Variables Scroll to the bottom of the list, and click the dummy variable dmajor1.

18. © Copyright 2000, Julia Hartman 18 ANCOVA (Regression Approach): Selecting Variables Select both dummy variables by holding down the Shift key and clicking dmajor2.

19. © Copyright 2000, Julia Hartman 19 ANCOVA (Regression Approach): Selecting Variables Move both dummy variables ( dmajor1 and dmajor2 ) to the box labeled Independent(s): by clicking the arrow.

20. © Copyright 2000, Julia Hartman 20 Click the OK button to run the ANCOVA (regression approach). ANCOVA (Regression Approach): Run the Analysis

21. © Copyright 2000, Julia Hartman 21 ANCOVA (Regression Approach) Output: Variables Entered The labels and format of your output may be somewhat different. Next

22. © Copyright 2000, Julia Hartman 22 ANCOVA (Regression Approach) Output: Model Summary Next

23. © Copyright 2000, Julia Hartman 23 ANCOVA (Regression Approach) Output: ANOVA Next

24. © Copyright 2000, Julia Hartman 24 ANCOVA (Regression Approach) Output: Coefficients Next

25. © Copyright 2000, Julia Hartman 25 An Interactive Tutorial for SPSS 10.0 for Windows © : ANCOVA (Regression Approach) Repeat this tutorial Click one of the following: Return to the list of tutorials

26. © Copyright 2000, Julia Hartman 26 An Interactive Tutorial for SPSS 10.0 for Windows © : ANCOVA (GLM) Repeat this tutorial Click one of the following: Return to the list of tutorials

27. © Copyright 2000, Julia Hartman 27 An Interactive Tutorial for SPSS 10.0 for Windows © : ANCOVA (Regression Approach) Repeat this tutorial Click one of the following: Return to the list of tutorials