1 / 17

Statistics in SPSS Lecture 8

Statistics in SPSS Lecture 8. Petr Soukup, Charles University in Prague. Analysis of variance. What is it all about ?. Title : Analysis of variance BUT THE GOAL IS: to find difference in means (see next slide) ANOVA – AN alysis O f VA riance SPSS – many procedures. Basic idea.

karentaylor
Download Presentation

Statistics in SPSS Lecture 8

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Statistics in SPSSLecture 8 Petr Soukup, Charles University in Prague

  2. Analysis of variance

  3. What is it all about? Title : Analysis of variance BUT THE GOAL IS: to find difference in means (see next slide) ANOVA – ANalysis Of VAriance SPSS – many procedures

  4. Basic idea IDEAL CASE B IDEAL CASE A BIG DIFFERENCE IN MEANS NO DIFFERENCE IN MEANS ? AND WHAT ABOUT VARIANCE ?

  5. TWO SOURCES OF VARIANCE 1. WITHIN GROUP VARIANCE IDEAL CASE B IDEAL CASE A BIG WITHIN GROUP VARIANCE SMALL WITHIN GROUP VARIANCE ? AND WHAT ABOUT BETWEEN GROUP VARIANCE?

  6. TWO SOURCES OF VARIANCE 2. BETWEEN GROUP VARIANCE IDEAL CASE B IDEAL CASE A x x x x x x NO BETWEEN GROUP VARIANCE BIG BETWEEN GROUP VARIANCE

  7. BASIC IDEA IDEAL CASE B IDEAL CASE A SMALL BETWEEN G. VAR. BIG BETWEEN G. VAR. =? =? BIG WITHIN G. VAR. SMALL WITHIN G. VAR. RATIO FOR TWO SOURCES OF VARIANCE CAN BE USED FOR FINDING STATISTICAL SIGNIFICANT DIFFERENCE IN MEANS

  8. ANOVA hypotheses H0: means for all groups are equal in the whole population H1: at least two groups are different in means in the whole population

  9. Output from SPSS TEST Sources of variance

  10. Data and sssumptions for ANOVA DATA: 1 cardinal variable (DEPENDENT) – e.g. income, satisfaction, lenght of education 1 variable that discriminnate into groups (FACTOR) – e.g. Level of edcuation, region, type of customer (Note: For two groups we use t-test) ASSUMPTIONS: Normality of dependent variable Equality of variances (Levene’stest), Independence of groups

  11. ANOVA in SPSS Analyze»Compare Means»One-Way-Anova Outputs and comments Post-hoc tests - 2 types, logic of multiple testing and Bonferroni correction formulae Eta2 – effect size for ANOVA

  12. Final notes More factors can be used two-,three-factors ANOVA In case of small samples use nonparametric alternative (K-W test)

  13. ALTERNATIVES TO T-TESTS(NON-PARAMETRIC TESTS)

  14. Alternatives to T-tests

  15. HW

  16. HW7 Try to test difference in means (one cardinal variable) by ANOVA. Interpret results.

  17. Thanks for your attention

More Related