Different Tests

Question 1

Difference in means tests

Answer 1

1 - Nominal DV
=> Chi-square tests//binomial sign for related

2 - Ordinal DV
=> unrelated : Mann-Whitney // Kruskal Wallis
=> related: Wilcoxon // Friedman

3 - Interval, Ratio DV
=> unrelated: unrelated sample T-test // randomized (one way) ANOVA
=> related : related T-test // ANOVA repeat measures

Question 2

Correlational tests

Answer 2

1 - Nominal
=> no possible -> equivalent is Chi-square 2x2

2 - Ordinal
=> Spearman‘s rho correlation coefficient

3 - Interval, Ratio
=> Pearson‘s product moment correlation coefficient
=> r between -1 and 1 -> strength of association between two metric variables

Question 3

Assumptions for correlation

Answer 3

1. Metric variables
2. Normality (histogram) -> Skewness (-1/1), Kurtosis (-3/3)
3. Linearity
4. No outliers (boxplot)

Question 4

Assumptions for regression

Answer 4

1 - Identical to correlation
2 - Influential cases (Cook‘s distance <1, CVR ratio 1+-(3(k+1/n)) )
3 - Homoscedasticity -> Plot residual for predicted values
4 -Multicollinearity -> ViF (variance inflation factor) <5