1. Statistics in SPSS Lecture 9
Petr Soukup, Charles University in Prague

2. ALTERNATIVES TO T-TESTS (NON-PARAMETRIC TESTS)2

3. Alternatives to T-tests
data
Parametric test
Nonparametric
a) Two-ind. Samples
Two ind. sample t-test
Man-Whitney test
b) Two related samples (paired)
Paired t-test
Wilcoxon test
c) More ind. Samples
Analysis of variance
Kruskal-Wallis test
d) More relateds samples
Friedman test 3

4. Alternatives in SPSS Analyze-Nonparametric tests-One sample
Analyze-Nonparametric tests-Independent samples
Analyze-Nonparametric tests-Paired
Example: alternative to ANOVA: Analyze-Nonparametric tests-Independent samples-Compare Medians (Kruskal-Wallis with multiple comparisons) 4

5. CONTINGENCY TABLES 5

6. Contingency table (CT)
Combine at least two (nominal or ordinal) variables in one table
Main goal: to analyze relationship between variables
Descriptive stats in CT: observed counts and percentages (row, column and total)
Analyze-Descriptive statistics-Crosstabs (Cells) 6

7. Test for CT Test of independence: Chi-square
H0: variables are independent (in the whole population)
H1: variables are dependent (in the whole population)
Analyze-Descriptive statistics-Crosstabs (Statistics)
Computation: comparison of observed and expected (by H0) counts
Note: for correct computation 80 % of exp. Counts>5 and no zeros 7

8. Contingency coefficient (CC)
Effect size for CT
Measurement of relationship between variables
Usually computed from chi-square
Values between 0 (no relationship) and 1 (perfect relationship)
Mostly used coefficient: Cramer’s V
Analyze-Descriptive statistics-Crosstabs (Statistics) 8

9. Detailed analysis in CC
For proven relationship (reject H0)
Sign scheme for adusted standardized residuals
Once again rule of values -2 and +2
Signs instead of residuals and it’s meaning
Analyze-Descriptive statistics-Crosstabs (Statistics) and MS Excel tool for sign scheme 9

10. HW 10

11. HW9
Try to analyze relationship between two nominal or ordinal variables by contingency tables. Interpret results. 11

12. Thanks for your attention12